Apple’s iPad needs its own operating system to become, as CEO Tim Cook has said, “the clearest expression of our vision of the future of personal computing,” some analysts argued today.

Cook’s characterization — made in September at the roll-out of the iPad Pro — was taken up by Jan Dawson, principal analyst at Jackdaw Research, who lobbied for a new operating system largely based on iOS as it stands today.

“If [Cook’s comment is] truly the case … then the iPad Pro can’t just borrow iOS from the iPhone,” said Dawson in a piece published on Tech.pinions last week. “It needs to have a dedicated operating system designed first and foremost for this device and not primarily for the installed base of 500 million or so iPhones in the world.”

In part, Dawson contends that the iPad Pro lacks first-rate support for the optional keyboard Apple sells, and blamed iOS. “It’s hard to avoid the sense … that Apple was somewhat hamstrung in its approach to the iPad Pro by not wanting to break any of the iOS conventions, most strikingly that it should always be a touch-first operating system,” he wrote, citing other elements, including the home screen design and multi-app windowing, as areas of possible improvement and enhancement.

Apple has forked iOS several times already, most recently for the Apple Watch (watchOS) and the Apple TV (tvOS), to modify the mobile operating system for vastly different form factors and provide each an optimized UI (user interface). It could do the same to create what Dawson dubbed “padOS.”

“Why should we assume that [iOS] is the right OS for all devices?” Dawson asked in a follow-up interview. “Why couldn’t they reinvent this like they have for the Watch and [Apple] TV? Is iOS really the best OS for everything from 4-in. phones to something the size of laptop?”

Dawson’s point was that it would be well worth Apple’s time to find out by building padOS, rather than add to iOS bits and pieces which, while specific for the iPad, in some instances for the iPad Pro, are wasted on the iPhone and vice versa.

“iOS is constrained by all the things that iOS connotes to people,” Dawson said. “If we were designing the iPad Pro’s [operating system] from scratch, would we really come up with iOS again?” he asked, putting himself in Apple’s place. “That’s spectacularly unlikely.”

Others agreed. “There’s a potential for a UI [user interface] more appropriate for a larger tablet that is still worlds simpler than a personal computer UI,” said Ezra Gottheil, an analyst with Technology Business Research. “There’s space here for a device that is less complex than a PC, but bit more complex — with keyboard and windowing — than what a tablet wants to do.”

For Gottheil, the iPad Pro — and other devices like it, often labeled “convertibles” or “2-in-1s” — is, because of its size, a different beast and not the typical tablet. And it deservs an optimized UI, and thus likely a tweaked if not different operating system.

“By marrying the simplicity of iOS and the hardware of a larger tablet, it could break out of the ‘it’s just a larger iPhone’ paradigm,” Gottheil added.

Crucial, he said, were an OS that offers a keyboard-oriented interface, with all that entails, including precision pointing and windowing, or at least the ability to look at more than one thing at a time. The latter doesn’t need to be as complex as, say Windows or OS X, with multiple windows that can be layered and shuffled around at will, but could mean halving the screen, or quartering.

iOS 9 offers Split View to the iPad Pro already, as well as other multitask-driven features, such as Slide Over and picture-in-a-picture for viewing video.

All the Big Three operating system makers — Apple, Google and Microsoft — wrestle with the problem of finding the best fit of OS and tablet, with the touch-based operation that the latter implies, but which may be largely moot when a keyboard is introduced to make the device more laptop-like.

Google, for instance, recently unveiled its first home-grown tablet, the Pixel C, that can be equipped — is meant to be partnered — with an optional keyboard. Google chose Android, not the Chrome OS that powered its clamshell-style notebook, the Chromebook Pixel, and those of other OEMs (original equipment manufacturers), who have done well in education with their more generic models.

Microsoft took a different tack. After a false start with Windows RT, the touch-only offshoot of Windows 8 — earlier this year, it orphaned those users who had taken up RT — the Redmond, Wash. company settled on squeezing its full-fledged personal computer OS, first Windows 8, then 10, into its own 2-in-1, the Surface Pro.

Like Apple and Google, Microsoft sells an optional-but-it’s-not-optional keyboard with the Surface Pro 4 tablet. But as a marker for the OS running the device, Microsoft’s keyboard is the only one of the three companies’ to have a built-in trackpad, a necessity, Gottheil said, for keyboard-centric productivity chores.

“It’s really about the use case, not the inches,” said Brian Blau of Gartner, countering the argument that the iPad Pro — or any larger tablet — requires a new or modified operating system. “As the device gets bigger, from the use case profile we’ve seen, iPad is used in business in a lot of scenarios. And there’s a lot of evidence that says it’s okay as is.”

While Blau acknowledged that when a device is different enough it deserves its own OS — and that Apple “may be able to add things” to the iPad’s skill set with an operating system forked from iOS — he had not see any evidence from businesses that they balked at the tablet because of its current OS.

“It does raise some questions [including], ‘Is iOS fully up to the task of supporting businesses with tablet computing?’” Blau said. “So far, the answer has been mostly ‘Yes.’”

In many ways, the issue becomes one of where to draw the line when defining “tablet” and “notebook,” Blau added. That line is changing and will become even more blurred down the road. Microsoft, for one, hopes so: It’s aggressively promoted the Surface Pro as a tablet that can replace a notebook. Cook questioned in an interview last month why anyone would bother to buy a personal computer after the iPad Pro’s appearance.

An operating system must keep pace with changes in a device’s use case, Blau contended, but again said that there is not strong evidence that the iPad in general, or the iPad Pro specifically, is now at a pivotal point where iOS is not good enough as is. But that may change.

“Eventually, there will be a tighter coupling between the [desktop and mobile operating systems],” Blau said “I think we’ve always thought that the more portable OSes will move upstream, but they may not move to the level of OS X and Windows.”

By “upstream” Blau meant not only larger form factors — larger screen, in other words — but also increased flexibility and thus an expanded portfolio of use cases.

None of the analysts felt qualified to suggest more than the most obvious changes to iOS to optimize it for the iPad Pro. Dawson, for example, would leave that to Apple’s experts in UI and OS design.

But like good art or pornography, Dawson would know a suitable 2-in-1 OS when he sees it. And iOS isn’t it.

“It’s hard to put my finger on it,” Dawson admitted when asked why as-is iOS isn’t the right operating system for the iPad Pro, why Apple should craft a padOS and risk fragmentation within its tablet line. “But [as to] the lack of keyboard support, to what extent is this because they’re trying to maintain the iOS experience?” he wondered.

“How can we take the iPad even further?” Cook asked rhetorically in September before revealing the 12.9-in. Pro.

Maybe by not just making it bigger, but different, Mr. Cook.