The advantage of segwit is that it elegantly fixes a couple of other hard problems (malleability, O(n^2) sigops issue)
What about fixing those "other problems" (I don't want to say "hard", because IMO they aren't "hard" by themselves) without the segregation? Impossible or just not worth it?
I don't claim to know the answer to that question, but your reply begs the question: Have you submitted a pull request with code that fixes these problems that you see as 'not "hard" by themselves'?