What I'm getting at, is a MPEG editing tool can not "in general" do as good of a job at editing as pure uncompressed avi editing program. Since MPEG video is made up of keyframes (I, P, B, etc) you can not always make a cut exactly on the frame you may want. Same goes for avi's with keyframes (xvid, divx, etc). There are naturally some exceptions like Womble and what not, but the average user becomes frustrated when Nero, Bobs All in One "Video" editing app, etc, do a crappy job for what they are trying to accomplish.
Premiere, Vegas, etc video apps get a bad rap because they can not edit DVD video as well as an uncompressed avi. But those apps are the wrong choice for the average user.