Seems a lot of people are forgetting that going giant isn't Ant-Man's only card here. Bloodlusted, he's gonna be shrinking and growing opponents left and right. It took him days just to figure out how to move around effectively, let alone fight. Probably the only one who will adjust fast enough will be Vision because of his computer brain. Everyone else will be sitting ducks. Heck, we can't even say that shrinking the Ironman and War Machine suits will also shrink Tony and Rhodey inside. They may just get crushed.
I was already expecting whole teams of heroes in both Marvel movies. One or two more made little difference.
A secondary villain would've been fine, but a significant threat like Doomsday? From the moment I saw him, I knew there would be a compromise between his and Lex's development instead of either major villain being fully fleshed out in their own respective movies.