What really irritates me is that Blizzard doesn't seem to care what will happen to guilds built around fielding a 40 man raiding force. What's going to happen to the 15 people who won't be able to raid with their guild anymore? And recruiting more people to run two raids at the same time isn't a good idea: I was in a guild that ran two raids at the same time and the amount of drama created by it eventually led to the second raid breaking off and forming a new guild. Actually, to run with that story, they tried to form a second raid group again and it worked for about 3 months before the secondd group again broke off and formed its own guild.
Basically, with the change away from 40 man raids, Blizzard is screwing over a huge number of guilds and they don't even remotely care.
/will probably stop playing WoW because of 25-man raids.