This is a rather unusual case involving a MAJOR case of the left hand not knowing what the right hand was doing...
But in my case, as a deaf guy who depends on closed captioning or subtitles in movies, the "upgrade" to high resolutions screwed up one thing: Everyone forgot about closed captioning.
This thread does a much better job of explaining it than I ever could: http://www.avsforum.com/avs-vb/showthread.php?t=699933
Bottom line: If I get a DVD that does not (for whatever reason) include subtitles, but instead only offers CC, then I must watch it in 480i in order to view the captioning.
I can't tell you how annoying it is to pop in a movie, see no subtitles, then fumble around with the PS3/TV settings until it works (and even then I end up watching the movie on my laptop because it's just easier that way).