I agree with this. On a side note, why did greenoaks have to say why he/she disagrees if those who agree did not have to state why they agree. If the intent of the thread is to gauge interest, simply disagreeing helps with that. It just doesn't help the op change the suggestion. If one does not like the suggestion at all, they may see no way of improving it, and therefore not waste their time explaining why they disagree just to start an argument.
Back on topic, I think that this would be great because it would make me less wary of joining games on maps I am unfamiliar with, without having to wait for the last spot to ensure I don't lose to someone who spends all of his/her time on that map. I don't mind losing, I just want to be able to get a feel for a map before I play the sharks.