So what happens if all the people who aren’t bothered are given an easier way to get to the group content that they want? (Remember, they don’t hate the server community, they just don’t care either way.) But server communities have been valuable for people. By running server-based PUGs, new players can mix with existing ones. It has been one of the standard ways that people find guilds (or guilds find people).
Even as a part-timer, I've got to say I've enjoyed the community created by PUGs.
I waited for weeks to get into the Caverns of Time to finish up a rep-based armor set, and finally gave it up. Turns out there was another fellow on my server essentially doing the same thing. We both kept ending up in the same groups, doing quick runs we'd already done in the hope of convincing them to go CoT afterwards.
And yes, PUGs do, as Spinks points out, encourage guild formation. I've run with several good tanks and healz whose playstyle showed, well, showed they were at the very least extremely mature 15 year-olds. When I was considering running raids, these were the guilds I researched online. And after noticing some quiet folk -- not folk I'd necessarily want to play with on a regular basis, as they after would whine like crud at the 15 year-olds who weren't so mature (often the Warlock. I don't know why, Warlocks, but the young folk IRL flock your way), but good, solid, get the job done folks -- running with great gear, I started noticing that their guilds were the first to finish server-wide accomplishments. Opening gates, bringing down bosses first, etc.
To lose that sense of community would be to further commoditize players in a way that might work short-term, but I believe would get rid of the hard-core folk who drive game adoption.
There's an easy compromise, and I'd imagine Blizzard's already given it some serious consideration -- ensure that as few servers as possible are represented in any PUG, and reuse those server combinations. If I need two more to run CoT, then pull them both from the same server. Later, when others do the same thing, pull the extra folk from that sister server. And encourage server transfers at times between the two.
If Apple can Genius up decent playlists, Blizzard can algorithm cross-server groups.