Maybe, but I don't know if that's a fair comparison. Frank had completely different goals with those two albums. Just Another Band from L.A. is a chronicle, a document of a band and of a performance. Joe's Garage is a concept album, a story, and a political statement.
I'm not sure if comedy was one of the goals of Joe's Garage; it seems more like an aspect to his writing that couldn't help but show up. More than anything else, it was meant to make you think, and hopefully entertain you along the way. JABFLA was primarily meant to entertain, and if it gave you anything to think about, that's fine too. Frank got into more "serious" music and issues later in his career. This may have lessened the breadth of his appeal, but like anyone else, I'm sure he got bored with doing the same things all the time.
Anyway, I came into this thread to report that I heard "Blessed Relief" from The Grand Wazoo on the radio today, on the local listener-supported jazz station, WDCB from College of DuPage (Chicago area). A jazz station! Fucking awesome. I heard the title track a while back, too. Apparently somebody got ahold of The Grand Wazoo and has been having fun foisting it upon unsuspecting jazz fans.