There is a flip side to this. Difficulty. There is no middle ground at present.
You have ONE extreme which is LFR,
then you have Normal which is far harder than previously in Wrath.
Heroic is just as brutal as it has always been.
You also have 10/25 being the same lockout.
So this kills pugs as sharing the same lockout means you are only going to turn to LFR for upgrades where as previously you could run a pug in 10/25 normal and get some items.
Flex will help people who want a bit more of a challenge but a fairly pug-able experience. I can't remember if it will be on a different lock out to 10/25 (It better fucking be tbh)
LFR does not kill guilds its merely the only option for a lot of people. We needed flex a long time ago to give that middle ground and a way for pugs to get going again on a big scale. Pugs help more people get into guild raiding and were quite a good bit of fun.