There's nothing wrong with that. You seem to imply that it must be all or nothing... either separate tools or all-in-ones. It's not an exclusive-or situation. Offer both!
Well, "done right" is in the eye of the beholder.
Here is what I would consider "done right" for such a device. Apple is SO close with the iPad Pro. For the sake of simplicity...
Take the current iPad Pro and add...
- Support for a mouse/trackpad. Make it optional as it is with Android. They've implemented it perfectly.
- Support for a file system that is universal to iOS. The current implementation of the Files.app is a band-aid on top of the current limitations within iOS.
- Support interaction with industry standards and not limited to Apple's ecosystem. Although macOS devices are Apple products that work well within the Apple family of products and services, they can also utilize industry standards such as USB, external displays, etc. in an open way. Android, Windows, ChromeOS, macOS, and Linux all can utilize peripherals without the need for proprietary connectors and protocols. iOS needs to do so as well.
None of these would compromise the simplicity and easy of use of iPads in their current mode of use, but would allow for the OPTION to use those things as the user sees fit. Want to keep using the iPad Pro as it is today? No problem, rock on. (these additions won't interfere with that)
It isn't necessary to take all of iOS and merge it with all of macOS to get a proper converged device. That is the conventional thought on that, and it's the easy way, but not what I'm advocating.