I should also say, I completely understand either being nervous, feeling underskilled, or simply judged. I get that it isn't comfortable. Unfortunately much of being a writer or an artist will put you in that place. The spot light shines on YOU, and you feel judged. It goes with the territory. We cannot hope for acclaim without openning ourselves up to the possibility of people liking or not liking.
As I mentioned above, critique is not simply like or not like, and it is far, far harder and will take far, far longer if you try to learn from the sidelines.
The point is, it's not half as scarey as it seems once you get started. The more you put into it, the more you will benefit.
The drawback of giving critique?
It takes a little time out of your day.
You offer a critique to someone who takes it peronally. ie they think you have critiqued them, not the song
At first it seems a little uncomfortable
That is literally it.
The benefits?
Your songwriting will benefit
Your songwriting skills will improve across the board
You will improve far faster than a writer who only works on their own
You gain experience writing in genres outside your comfort zone and learn from people who do write that genre
You learn to make songs with broader appeal, that are more memorable
You learn how to convey exactly what you meant and gain an insight into how it could be received
Your observation improves hugely
Your analysis skills improve hugely
You build a far larger assortment of possible solutions you can offer
You learn to work faster and more efficiently, arriving at a genuinely completed song with less songs that are never finished
and more...
PLUS
Members see you taking part
Members see you reciporicate their efforts
Members help you
You make friends (you do use that feature don't you?)
You build a good reputation amongst your peers
It makes you feel warm and fuzzy inside
Hopefully you take all this in a constructive way and hopefully you will see benefits a lot sooner.
Cheers
John