Because having an army of peak human soldiers is very desirable.If the Super Soldier serum doesn't make you super-human why in the world would there this massive global race to re-create it?
Even that's debatable. The marginal payoff of a "peak human" driving a tank and a regular guy driving a tank strikes me as not particularly substantive.
Anyway, Tony Stark is more of a dick. That's what this thread's about, right? No? I really hope it wasn't about whether Bruce Wayne could beat up Tony Stark, because that's not much of a discussion.