I have always wonderd this myself also.
There have been times where the line has been out the door at the baggage office where a dedacated line or CSR for elites would come in handy. I think this is something we should bring up if UA has those meetings for 1Ks in DC and NY like they did last year.
I feel if there is a dedicated chekin line, a security line, boarding line (SFO), why can't there be a baggage line.
Ben