In Wrath you could have new players go do 10 mans to get geared enough to do 25 mans and to get some experience.
Now you have to both gear and get experience in 10 mans, when your guild only do 10 mans ofc. That's harder imo. Cause as several of you have already stated, there are less margin for personal errors on 10 man.
On top of that, it's alot harder to organize a 10 man guild than alot of ppl tend to think. It's not just about getting 2 tanks, 5 dps and 3 healers to log on. On several fights you need particular classes and as a 10 man guild you don't normally have 20 ppl to pick between. It's a very sharp edge to balance the number of ppl you have in your roster. Too few and you will have a hard time getting the "right" setup. Too many and you will have to bench several ppl. Alot of ppl will simply leave and find a guild where they wont be benched and with the amount of 10 man guilds popping up all the time, that's not at all hard.
Add to that the difficulties 10 man guilds have when it comes to recruiting. Cause you can't just recruit a random dps. Atm we are a dps short, but that dps has to be an ele shaman. With no mage and no shaman in the roster, we need an ele shaman (no room for more melee) to get BL.
Loot wise; I don't think I've ever experienced worse loot drop tbh. I've been raiding for almost 2 months in the same guild and gotten 1 piece of MS loot. Why? Cause nothing else has dropped, that I couldn't get from VP/rep. Meaning I havn't seen the leather shoulders on Omno, the staff from Halfus or the trinket from Valiona a single time. (Got 2 items with another guild back in late december though).
Point is, as the main tank I've gotten zero loot for weeks now. Don't remember ever have this happen in the prior tiers tbh.