I'd love to hear more discussion on this topic, as ZarroTsu mentions we currently have only allowed community reviews to be approved if they have an "overall rating".
It was originally considered a requirement based on the idea that members prefer having a conclusion based on a frame of reference that most members are able to easily relate to (ex: 1 to 10 rating).
ZarroTsu has a few questions that make sense, but what solutions are there?
Well, here are several that could replace the "overall rating" requirement:
1 - No rating requirement. No frame of reference.
2 - A subject-based rating requirement (at least one aspect of the game would be required to be given a 1 to 10 rating, ex: Gameplay would be given a 1 out of 10 rating or Story would be given a rating).
3 - More than one subject-based rating requirement (same as above, but would require more than one aspect of the game to be given a 1 to 10 rating).
Any other ideas?
I suspect that not requiring a review has potential problems, for example most members don't spend more than a few seconds reading a topic and will simply not read the review if it doesn't supply a rating for the game it reviews.
Also, without a frame of reference such as a 1 to 10 rating, a member may be unable to decide if the review gave an overall positive or negative perspective. Sometimes it's obvious, other times it's 50/50 and you really aren't sure where the opinion truly lies.
Of course, these might or might not be concerns for many members, but we won't know unless you tell us!
So join in and help discuss the issue!

(Unless of course you want us to decide everything without you and we won't be as willing to listen to complaints if you never contribute to the conversation. In other words, if the topic matters to you, then speak up!)