Keep in mind that when PIT was our largest base with 3000 F/As,1600 pilots and over 400 flights a day, it NEVER had the meltdowns that PHL is now seeming to encounter on a regular basis.
A BASE and a HUB are two different things.
Yes, the airport in PIT is nice. Yes, its cheap to live there and the operation ran smoothly because of the design and geography. But it's not a global city and not big enough to support a hub. If it was, another carrier would have gone in there. They haven't. Southwest went in with a handful of flights and hasnt added much since (compare to thier quick build-up in major cities like Philadelphia). It is not coming back as a hub for US or anyone else.
Philly has problems- some that are shared with New York and DC like geography, weather, overcrowded skies, and high cost of living/low paid employees. Some are unique (poor terminal design). But its one of the biggest metro area of the US, has huge O&D both domestic and international, and its responsible for 40% of Airways revenue. 40%! I would wager that the hometown airline is more of a problem than the city itself- they control morale, pay, operations, and terminal layout to an extent. If any base gets bashed its Philly because the majority dont live there and assume no one does. Meanwhile they live in places like Buffalo and Greensboro which while nice aren't exactly cultural centers. And no matter how many times US puts it on a napkin, I'm not sure anyone would consider Charlotte to be "cosmopolitan" relative to other east coast cities.
No airline is going to maintain a hub somewhere that can't support one for operational reasons alone. It's just not going to happen. PIT as a hub has gone the way of places like Dayton and Syracuse. And folks, theres another merger coming with another one of the big six. No matter which one it is, the measly 39 flights a day at Pittsburgh will be the first casualty. Its gone.
As far as a crew base goes, it depends on how they would like to staff. Many regional airlines have crew bases in outstations rather than at the hub. For example you may be based in New Bern or Harrisburg or Akron Canton even though the major operations are through CLT and PHL. Major airlines do not tend to do this because of the sheer size of thier operations. Bases tend to be in the hubs unless there is a specific reason for a base (like the DCA LGA BOS bases are for the Shuttle operation as well as the focus cities that remain there). PIT barely serves as a focus city, and the majority of the US flights are not operated by US but Republic, Trans States etc. There are 39 flights a day and that will probably shrink more- it's not going to be a crew base in the future, thats a reality-thats what people are trying to say here.
As for base jokes, thats at every airline. Its mostly in good fun.