There are far more factors in the RJ conundrum than simple pilot pay, # of seats, and fuel economy.

Limited runway slot constrained airports, gate space just to name a few. Doesn't matter who flies a 76 seat RJ if you don't have the runway space to takeoff/land, or a gate to park it at. EWR gate space is ridiculous, SFO and LAX have been at capacity for a number of years.

Larger planes, less frequency is the only solution until more infrastructure can be made. Long term problems, long term solutions must be found.