Yuratuhl wrote:
The skilled players don't necessarily get along well enough to want to do 10-mans, and sometimes there's just no interest in anything but the dungeons that get you the best loot.
This.
The core of any guild to me implies the people who run it, namely the officers, leads, and/or the advisors thereof. They don't necessarily have to get along to still function, as has been my experience (within several guilds).
In Twisted's case, as a for instance, out of our two regular 10-man groups, the furthest/fastest progressed 10m of the two is made up of regular 25m raiding members. The other, similarly progressed 10m has the GM and some officers/leads, although a noticeable less amount over the course of WoTLK from naxx to icc, due to schedule conflicts, disinterest, or demotion.
Success in pve accomplishments doesn't make a guild great. When the guild's environment is unpleasant and suffers, there is no guarantee that people will endure it and that the guild will be there tomorrow. Then all of that success will be for naught.