I'm not sure about the legal aspect, but I like the idea.
Should be fine though as long as you stick to ridiculing their decisions, and not attacking the Body Corporate or their members personally.

Maybe set up an anonymous blog and sign the letter with the url to that and invite comments from the residents as well?
Republish your newsletters there.
That way you get the residents involved and get feedback from them at the same time.

There's probably a lot of people in your complex who feel the same way you do and this would give them an opportunity to voice their issues as well.
Currently with the body corporates they don't care what residents think and seem to be a law unto themselves.

Gather enough support via the blog and then that body corporate is in for a really hard time.