It is downvoted because it's a useless criticism with no value to anyone. Original poster "put himself outthere" in a way that is helpful to the community, and that guy was just trying to be mean and probably hasn't done anything himself. Downvoted to show original poster that we appreciate his response and do not support troll-like behavior.

Pointless negativity is generally much worse for a community than pointless cheerfulness. You're allowed to dislike anything at all, but this community requires that you express that dislike in a way that's a little more thoughtful than "Your app blows." fairlyodd's comment was wildly inappropriate for the context it was in.