Well if the U-wing is more of a transport than a fighter, it’d make sense that it doesn’t appear in any battles. Then again it doesn’t look like a transport so who knows.
From what they said on The Star Wars Show, it’s more of a fighter/gunship/transport (kinda in the style of the Republic Gunship, I guess). So it can probably only hold a squad or two in the bottom part.
It’s been growing on me. Still not my favorite design.