To be fair to Beltran and Wang, the writers did give them nothing.
A character with a gimmick is easy to write for. Any one of us could come up with a dozen hologram stories off the top of our heads. Chakotay has no gimmick. He has one element of 'non-white-male-human'-ness, he was Native American. The writers know nothing about Native Americans, but they're like, all spiritual, right? Ok, look up a few spiritual Native American stuff and make episodes around it. Episodes that have nothing to do with his gimmick? Oh, way too hard, that would mean they have to be creative.
O'Brien had no gimmick either (Unless you count being married) and he got Whispers, Hard Time, Visionary, and The Assignment.