40-man raids are just overrated, most of the time 50% of the people would do all the work, and the other 50% would just slack around and get the shinies for no work at all.
Furthermore, they we're close to impossible to administer. Keeping an eye out for every single member in a 25 man raid can be hard, imagine if you we're to drop an additional 15 noobs in there too.
Noway, I'm happy with the way things are now.