I've been using the beta version of iPadOS 15 for the past month. It isn't a huge update, but it definitely fills in a few of the most glaring gaps on the iPad. It's also remarkably stable for a beta. Overall, it's very good.
Well except Safari, which is really bad. It's bad enough that if Apple doesn't make some changes, it may well lose its status as the most widely used mobile browser.
Mostly it's bad because the new version of tab management in Safari makes it a lot harder to use tabs. Anytime you add a feature that makes it harder to do something people use on a regular basis, that's a problem.
Setting Safari aside, iPadOS 15 is almost everything the iPad needs. It improves multitasking, brings widgets to the Home Screen, and adds the App Library to the dock (you can remove it if you like). Those latter features were notably missing when Apple added them to iOS last year, but now the iPad gets its own version of both.
I say almost because I'm open to the idea that there's room for improvement, and that there are things that would be nice to have on the iPad: Better control over how you arrange icons on your Home Screen, or better file management as two examples. To be clear however, macOS is not one of those things.
Yes there are some things that are harder on the iPad with iPadOS. There are things you can't do using the iPad that you can do on the Mac--that's why Apple still makes desktop and laptop computers.
I think iPadOS 15 makes clear that Apple is never going to put macOS on the iPad. There are plenty of people who are going to say that I'm wrong and that Apple should put macOS on the iPad. That's not the same thing, by the way, but it's also not the point.
The iPad isn't a Mac in another form, which is what you have if you put macOS on it. It's something different. It's something you use for different reasons, to do different things.
Saying that the iPad should be able to do all the things a MacBook Pro should do ignores the fact that there's a reason Apple makes both products. If you want to do MacBook Pro things, you buy a MacBook Pro. That's not complicated.
Most of the people who are asking Apple to put macOS on the iPad are using it with a keyboard, I suspect. Perhaps the Magic Keyboard, which also gives you a remarkably good trackpad considering the form factor. But that's not how most people use it.
For the rest of the iPad users, having macOS would be a nightmare. That operating system was never meant for use with a finger on a handheld device. iPad OS was meant for exactly that. And Apple has expanded its functionality and capabilities to accommodate more use cases with a keyboard, trackpad, and Apple Pencil. There's a limit, however, to how far you can push it without breaking things for people who just want an iPad.
I've also heard iPad users say they want to be able to run Apple's pro software on an iPad with macOS, preferably connected to an external display. To which, I respectfully suggest you might be happy with one of the colorful new M1 iMacs.
I know things got confusing when Apple put the M1 in the latest version of the iPad Pro, but keep in mind that while Apple doesn't break out sales by specific model, the iPad Pro most certainly represents a very small fraction of the total number of iPads sold each year. Just because it has the same hardware doesn't make it the same device--it clearly isn't.
Also, I know that there's an argument that the iPad Pro is for power users and as such, it should do power user things. Except the MacBook Pro doesn't run software that the MacBook Air can't, and they have the exact same hardware. Well, except the MacBook Pro has a fan and a Touch Bar, though I'm not sure those are features any MacBook Air user is missing.
And the MacBook Pro doesn't run a different version of the operating system than the Mac mini or the iMac. They are all Macs. Apple isn't going to make the iPad Pro run a different operating system than the iPad or iPad Air. They're all iPads.
Thankfully, Apple put thought into how to make the iPad's multitasking better in iPadOS 15. While I think there's still room to improve, this is a good step in the right direction. Instead of remembering which gesture will give you the multi-app layout you want, there is now a three-dot button for each app. When you select it, it lets you decide what to do with that app.
It could be better. It would be great if side-by-side mode worked more like slide-over, where you could create a stack on each side and swipe through each column. That would make it much easier to move between more than two primary apps.
Apple seems to have so far resisted the temptation to try and make every product for every possible customer. Doing that might seem like a good strategy, but the problem is, you don't really make anyone happy. Instead, Apple is making each product do what it is best at. If you need a device to do something different, it makes that as well.
That is to say, the thing you need on an iPad isn't macOS or even Mac-like multitasking. The thing you really need is for the iPad to be better at its form of multitasking. The latest version is getting a lot closer--close enough that I don't think we'll ever see macOS on the iPad.