I definitely have to agree with what most people have said in this thread ~ that being that I'm in support.
There have been several occasions where I have been able to get really far into a map of a reasonable difficulty (for whatever skill level I am at the time) with pretty high accuracy only to lose it all at the end. I still want to be able to use the replays both so that I can improve on it or to show to others.
This can also be used in compilations, having looked around youtube, I do see videos of people posting osu compilations of certain sections of maps and I feel that this could be improved by enabling the saving of failed replays, often the segments that a lot of people will want in videos like that will be of maps which for the most part they feel are beyond their skill level. I remember before (quite a little ways back now
) always being ecstatic at beating even the first section of Scarlet Rose and it was the sort of thing I wanted to be able to show people at the time. I still feel this with some maps now too.
In terms of the grade issue ~ I'm not sure it's too much of an issue any more as people have, for the most, part agreed that an F would be fine.