I would love for Marshall to get more attention, though I want it only in the professional world. Frankly, I don't want to see wifie and the kid. I love seeing the photos of Mitchell, but bringing baby to work or seeing them at home would make me cringe!
I also want good writing, not some of the stuff we've been offered in S3 and even S4. It's been hit or miss. The "We had eggs" thing about Sark was priceless (though I've since read that Kevin ad-libbed that!) Maybe Kevin should write his own lines all of the time!
Episode #16 is supposed to be a "Marshall" episode, according to another board. The title is "Tuesday." I haven't found a description, but it's supposed to be a Marshall mission. I hope it is well-written!
I would like the gang to show more respect to him, too! In the S4 premiere, when Vaughn said there's only one guy he would trust, meaning Marshall, they brought him into the fold of APO. One would think they would show Marshall a little more respect since they "trust" him so much! Yet, they continue to snap at him. What was it last week -- the "stop picking on me" line? While it's done for laughs, I wind up not laughing. Instead, I'm annoyed with the writers for not coming up with something no more humorous than what amounts to kicking a puppy. Everyone in APO should know by now that Marshall gives his all. I think Kevin and Marshall can be funny without people giving Marshall a hard time. Heck, we're in S4. That routine's a little worn at this point.
As for Kevin telling JJ, I get the feeling that all of the actors want more attention. Carl Lumbly (Dixon) complained about his having less of a role in S3 in an interview awhile back. The problem is that they are all on the same side now. It is a large ensemble, which always causes some problems with trying to distribute scenes and lines somewhat evenly. When they were on different sides, they had more to say. Now, there are no secrets to keep, no lies to tell, and so they have less to say and do, period.
I still like Kevin's idea of a spinoff series called "Marshall's Place" about a bar with Marshall and Weiss. I'd watch it!
They do need to mature Marshall, and some other characters, into the realm that the other main actors are in. Like you said, the routines can get old. Marshall carries the missions and they still treat him like some kind of misfit. If the show continues, they should change things. 
