Before I agree or disagree, I have to ask: are you equating the Modern UI with WinRT? Unless I'm mistaken, they are not the same thing. WinRT uses the Modern UI but the Modern UI is not exclusive to WinRT.
Having said that, I would disagree and state that WinRT does need to go away; if it looks like Windows and feels like Windows but doesn't run Windows apps then it's confusing.
At the same time, I recently upgraded my laptop from Win7 to Win 8.1 (I got the $15 upgrade to Win8 Pro way back when) and I'm getting used to the Start menu now being the Modern UI Start screen. When I remote in using Remote Desktop from my iPad, it feels quite natural and useful. When I'm at my machine and using a mouse, not so much.