That's one of the problems I've always had with the Monsters Inc. coaster, conceptually. I think the real reason TSMM is so packed all the time is that because except for TSMM, what rides are there that families with kids under 40" tall can even do??? (and let's face it folks - that's a
huge portion of WDW's annual attendance, most of whom are going to visit DHS once on their trip).
I guess there's always the 11th trip on the ever-popular-with-kids Backlot Tour or Great Movie Ride.
While most posters here enjoy multiple rides on Star Tours, Tower of Terror and RnRC to the point that they can enjoy a full day at DHS, the fact of the matter is that with the exception of TSMM, families looking for rides don't have much to do there... and so TSMM has to carry the load for the entire park.
What DHS needs is a family-friendly (re: no height requirement), high capacity attraction... something like what the Little Mermaid omnimover has brought to DCA.