LR already goes by Sac City College and an extension further south to Cosumnes River College is under construction. LR also goes by Sac State, but a 5-10 minute bus transfer is required to get on campus. An Elk Grove extension was in the works, but is currently dead due to lack of funds. Downtown Plaza is the only "major shopping mall" that I can think of. DtP however has been losing retail tenants the past few years, with companies migrating to other shopping districts, so the major part may no longer apply.
Because people don't like the riff-raffs in their neighborhood. Or as some put it, "people who don't belong there". A lot of destination sites would require encroaching on existing neighborhoods, and that is always a tough sell. The extension into South Sac was relatively painless because it follows the rail tracks. Places LR doesn't go are covered by buses.
This is one of the draw backs from not having locals involved and I never understood the yahoooos from people concerning that. These issues might be exactly why Cal Expo was not on anyone's radar until the outsiders got involved.
Though it would be nice, not having LR isn't a deal breaker for me. However I don't think it'd be any easier dealing with the state than with locals, especially in these economic times.
My point is, to have people use light rail, it has to lead to a destination that people want to travel to. Schools/colleges are a great location and you stated the problem, it only really services one college at this time (bus transfers, etc, are a pain and drop ridership). Yes, others are on the way, but I was referring to the service as it is. The colleges, airport, and malls are not new and the Sacramento LR service is over 20 years old. Poor planning has reduced ridership, not lack of interest.
I would
love to be able to catch a train in Elk Grove and go to the airport or the shopping mall of choice. Heck, I'd like to be able to get on in Elk Grove and go see the in-laws in Davis. But I have to drive to Sacramento just to find a station, and it is still out of the way.
Their 20-year vision map actually looks somewhat promising (at least they are finally getting around to getting to the airport and Elk Grove and Davis - where they should have been from day 1)....
http://www.sacrt.com/images/20year.jpg
This is supposed to be "regional" transit. It has been pretty much "downtown to Folsom, Watt Avenue, and Meadowview" transit. Not nearly the same thing....
There are several major shopping malls - including Arden, Country Club, and Florin (which were very popular when the RT lines were being planned, CC and Florin now not so much, but Florin is getting a new mall now). New large malls in Elk Grove and Roseville are popping up and could also use service.
A lot of the areas mentioned were also a lot easier to get to 20 years ago (including the airport - Natomas was fairly desolate then, especially compared to now) and would have required much less in the way of disturbance to neighborhoods.
There are also existing rail lines to Davis, Elk Grove, Woodland, Galt, and up to Elkhorn (which could easily shoot over to the airport) - the Southline extension isn't unique in this regard by any means.