A/V + (으)면 뭘 해요 is a response used to undermine a previous observation: ‘what’s the point of/so what if…?’. It is usually followed by a point considered more important – this often ends with A/V + 어/아/해 야지요:
말만 하면 뭘 해요? 실천을 해야지요.
What’s the point of talking? You should do something (i.e. actions speak louder than words).
남자 친구가 잘 생겼으면 뭘 해요? 너무 시끄러워 야지요.
So what if my boyfriend is handsome? He’s really loud.
그는 인기가 있으면 뭘 해요? 여자친구가 있어야지요.
So what if I’m popular? I don’t have a girlfriend.
춤을 잘 추면 뭘 해요? 유면한 사람이 되어야지요.
So what if I can dance well? I just want to be famous.
그 여자는 정말 예쁘면 뭘 해요? 머리가 텅 비었네요.
So what if that woman is really beautiful? There’s nothing in between her ears.
제가 키가 너무 크면 뭘 해요? 머리가 자꾸 부딪쳐야지요.
So what if I’m really tall? I’m always bumping my head.