@Seth That question is broad, but I actually voted to close it as opinion-based because I think that's an even larger problem for that particular question
(Also there's the potential for an edit to sit around in improvement limbo forever as more and more people "improve" it - not saying that'd ever happen, but it could. :))
Not necessarily difficult, just more complex. For instance, SE tracks stats about edits; if an "improved" edit gets rejected, should the original suggester, the improver, or both have their "rejected" stat increase?
Sometimes a users suggests an edit for tag wiki excerpts that needs a bit of improvement. As in the following screenshot, I wanted to remove the typos he introduced and leave the rest of his improvement.
However, I cannot "improve" the tag. The button isn't there. When I go to the tag, I cannot ...