They had the Carrier in the game. They decided to get rid of it. The Goliath is pretty darn straight-forward and dull.
I'll give you the Corsair, I think, but even then... and I don't think the Corsair's ability really fit it, I think it was sort of like the WC3 batrider, where they had two roles they needed/wanted filled (aerial siege capability, anti-air) and they just sort of shoved them together. Not that t wasn't cohesive, but there were better ways of doing it.
I REALLY don't see how those units would fix the problems they're having now.