Why do you want critique?

[wasellajam]

Poetry (especially in forms) is problem-solving, and critique (1) shows where the solution was bad or could be improved, and (2) presents new problems to solve.

Because/also, as a master programmer said about bug hunts, "I'm better than you are, and you're better than I am."  As a total amateur, I can still look at a published poet's work and (occasionally) find a problem - even suggest a solution.  And (drop the high-low) you can look at something I sweated blood over for weeks and put your finger on an obvious deficiency after one reading.  It's not necessarily fresh eyes, just different.

Also, it's a kind of socializing, and I don't go to bars.

Perfectly articulated.
Critique is indeed problem solving.

I would also say that to be a good critic, you need a lot of heart.
It is difficult to provide feedback on poems that bore you, and also difficult to comment on poems that sway you. Finding the patience to explain what you liked - and first of all, to really think about what it was that you liked or disliked - is not easy. Far more tempting to say “this sucks” or “this poem could only
have been written by a god”, out of laziness.

Which is one of the reasons I don’t post often in the critical fora. It’s asking a lot from a critic, and I go there only when I really, really want to workshop. The rest of the time it feels like an imposition. 

We’re too polite and considerate as a bunch, I say.

As a critic you also have to be willing to take the risk of seeming the fool. I totally missed the metaphor in 2 poems yesterday, or was it the day before? And sometimes I realize after someone else posts that I missed a subtlety that I should have caught. It's probable that if I wait until I'm sure I see it all I'll never get back there. So I read until I have a few things to say that could possibly help then post. The poetry police haven't come to my door yet.

I don't think we need to individually feel we're imposing or being imposed on, sometimes 5 half-assed crits can add up to one expert one.  I think it's best as a group effort.