There have been a number of really excellent changes mooted for 3.2 (the silly arena notwithstanding), but the one which has the potential to revolutionise the way I play is the proposed optional two week instance lookouts.
When I saw that Ulduar was due to have 15 bosses (or however many) my first thought was "What a shame that I'll never finish it". I raid one night a week - sometimes I arrange this so that I raid twice in one lockout period, but the second raid is midweek and hence shorter - maybe 5 1/2 hours total. We raid in a pretty relaxed way - we goof around, try to kill each other, we drink (heavily). We rarely wipe more than 3 or 4 times in an evening, but it's rare that we get more than one watcher down (our record is Freya and Hodir down, and on that night we called a halt because people were tired and downed Razor before calling it). Similarly I have still (STILL!) not killed KT - I have 4 or 5 wipes on him in total I think, including a 2% wipe where I had a five second lag spike in a void zone and hence died.
This lockout change will be brilliant. I'll be able to start the fresh Friday night run on Thorim every other week. The last two keepers are supposed to be tough, but if we can START on them and have 2 hours of practice before people's attention starts to wander then I'm certain we'll down them.
There is no downside to this excellent change, and it really helps those of us who can't raid regularly see the later content. It isn't "catering to casuals" because we still have to beat the bosses - it isn't a short cut by any means.