I do SFO-LAX for a few weeks at a time every couple of months and it would be very nice if they upped the frequencies. The new Eagle flights provide some flexibility but honestly landing at the remote terminal is such a time suck, especially for a short route like this. Also, I'm not sure when you're flying but often times in the mornings, especially on weekends, the captive market is tour groups and those making Int'l OW connections at LAX.
Hopefully when Compass starts flying for AA they get their hands on some 175's and go toe to toe with Delta on the shuttle service (which IIRC has seen a decrease in frequencies since it first started). The 175 is a great plane for this kind of route and perhaps the economics of connecting passengers to O&D can make it a bit more friendly...