It was only 5 years ago that the first iPad was released, and the iPad and iOS have grown tremendously since then. The more powerful these devices become, the more powerful iOS and its apps will be. so while I can understand people wanting OSX on an iPad, I really don't think sticking with iOS will hold it back going forward.
Tbh all I think Apple need to do to bring iOS up to on par with desktop class OS's is release their Pro software (Final Cuf, Logic...) onto the iPad the same way they did with Pages, Numbers and Keynote and try and fix a deal with Adobe to bring full Adobe apps to iPad in a touch based UI but with 99% of the features.
Then add mouse control (cursor or screen), and a file browser made for touch and done. That is what I'd call a pro device.