This is the first post i start, but i believe the idea is worth it. Lets spin it around and propose it to Blizzard later if we think it could work.
The biggest problem of LFR 25 man is the people that hide behind everyone else and do nothing or underperform a lot.
having 25 man filled with 5-10 ppl like that you can hardly kick them because it becomes a war and if you manage to kick 1-2 more will join and ppl will start ranting about delaying the already long Queue + dungeon run
Making LFR 10 man will only bring good things to the table
1. Easier to spot failure and easier to explain said person what he did wrong or replace him if he refuses to learn.
2. Easier to spot underperformance and be dealt with
3. Less players makes the time spent more sociable. People can use their social skills where in 25 man you only seldomly make some small chat via whisper.
4. 10 man will need more tanks and healers vs DPS Ratio than 25 man but that is good.
4.1 AFK dps-ers will not like to spend 1h waiting to get kicked after they refuse to learn so either they conver to active dps-ers or will soon stop doing LFR
4.2 Normal players will test being a healer or tank after a long queue and will probably enjoy it much more when they don't have to do all the work.
In Long term this change will make much more tanks and healers available within the game. And will also can start making the game more sociable.
Big raids might be fun but they brign the burden of someone Organising all that and the rest beign quiet so everything can run smooth when 1 is explaining.
25 man lets much mor emistakes go unnoticed and that's not a good thing. It Dumbs Out the WoW population and we see where that gets us every next day.