why is it so underrated or overlooked

I heard shows like modern family pay hundreds of thousands if not millions in gifts for the judges of the big TV award shows, the guys on this show seem to have too much self respect to pimp themselves out like that, this show isnt even first shown on FX anymore, you might hear of other shows more but this one has been on every year longer than any of them, the only other series on TV I can see making it to 12/13 seasons is the walking dead.

I would guess because the humour is very dark and there aren't really any likeable or even relateable characters.

They said it best. Kind of took a while for the show to pick up an audience. By the the show was already in its 3rd season. Critics were late to the show and never really looked at it again.A lot of those awards go to new shows and much of the others as other people said are on major networks or starring supercuck Lewis CK

Most of the super popular sitcom type shows appeal to the masses which have a far less developed sense of humor. It falls in with Arrested Development which didn't do that well as far as drawing an audience and was cancelled after only 3 seasons but is now considered one of the funniest shows of all time. It's kinda like the difference between a major blockbuster like Spider-Man 3 and a far superior indie movie like Safety Not Guatanteed.