No support Yes, it can get annoying but you can always scroll up to see what the person actually said, also, quoting long posts may get annoying, and thats why we need this option so we could cut the longer parts and make them a tad bit shorter to quote what you're actually referring to. Good idea, though.
Support! This has never happen to me, but I could imaging it being very annoying to people who had their post being quoted and modified.
Neutral, people do frame others, but it isn't hard to find the real source of the comment. And it's fun to do stuff like
The quoting feature is extremely useful and shouldn't be modified in the least; it's a valuable tool and it seems petty to remove the ability to do such editing to other posts. You have to be pretty sensitive and touchy for malicious edits to affect you to the point where the cons outweigh the pros of quoting and you should probably look for other alternatives (like spending an extra damn ten seconds to see the original post). People manipulating the words of others is hardly an issue when there's clear evidence against it and the abuse of quoting is almost harmless as is.