If only people could stop thinking like this... one can dream.
Same could have been said in Wrath: why would you want to encourage 10man if people don't really want to do it, as they prefer the more exciting 25man format.
Add to that the fact that new 10mans are formed each week (check forums); this combined with the fact that the game is loosing players only leads to 3 possible scenarios: either more non-raiders want to raid, or they come from a seemingly unending stream of 25man guilds breaking appart (which is not the case) or 10mans tend to break up way too often. I dare say 10man is not the fun loving place that 10man raiders advertise. 25 needs to be encouraged solely for the stability it provides: they might be splitting appart but it takes ages for them to do so (much more than a 10man anyway).