My mutt (12/6/2 fighter/ranger/monk) has PUGed many many times (in the new epic content too) with max-DPS barbarians or fighters who end up dying without a dedicated healer. The ones from the elite guilds usually bring a hireling along if we don't have one, or they chug silver flame pots, so they don't die a lot, but if they get knocked down for a second while surrounded, it's usually "Ding! Dead melee."
Me, I probably only do 70% of their DPS, but I NEVER die. I'm the one who always saves the party from the wipe.
Now, who do the elites want when they are doing a epic elite raid and they have the healers and casters in the group? The focused max-DPS barbs of course, and for good reason... they ARE more effective than my mutt in those roles.
But I enjoy being able to do any quest any time without problems. Some quests go easier with a ranged attack. I can do it with 6 levels of ranger and manyshot... More quests go better with a solid melee attack... I have it with 12 fighter levels, good weapons, and Haste Boost IV. I don't kill as quick as the max-DPS crowd, but I don't get hurt as quick either.
High AC, High Dodge, evasion, self-healing, UMD, decent ranged attack, decent melee attack.
All this is more useful in many quests and PUGs than max-DPS melee attack only builds.
Although again, in a static group or guild-only runs where every role is available, six highly focused builds will perform much better than 6 "generalist" builds. But a "generalist" build will do much better in most PUGs, and has the advantage of not having to wait for a healer or a caster.