There's a difference between giving criticism, and being plain old mean. Licensed developer or not, there is such a thing as tact.

If I say someone is an a-hole, that's one thing. If I say I'm not very fond of them, then that's something else entirely. They mean the same, essentially, but I've used a little tact.

Yes, one must learn to take criticism, however "that sucks" is not criticism. It's a put down.