I don't care for it myself for a lot of reasons, largely because it's by it's nature subjective. I can also see it leading to a very unpleasant playing enviroment as people try and kiss up to Valve indirectly, and they eventually wind up going Emo about "oh why oh why did this guy get a free game and I didn't?" The whining alone (and it will happen) is going to be a problem.
Also, given the fact that there is rarely going to be a person involved in looking at the complaints and ratings, simply due to the players vs. employees ratio, such a system is going to be a problem due to the way people "play" it. For example one of the reasons why I haven't done many fighting games online is because while bad at them, whenever I beat someone with a decent ranking they would ALWAYS put a complaint on my record for "unsportsmanlike conduct", this being an occurance on Xboxlive. The actual reason being that by putting a mark on someone's record it reduces the chance of them having to ever play someone who beat them again, which for someone looking to climb competitive rankings is an advantage. I'd hate for someone to say look at my Soul Calubur IV complaints and go "hmmm 78 unsportsmanship like conduct complaints, let's raise this guy's prices".
Not to mention how things unrelated to gameplay are going to creep into things like this. To be painfully honest, things like gay rights, racial politics, abortion, and other issues are hot button topics and represent major divides in the US, like 50-50 despite what the media says, which is why there are ungoing battles and people have to fight tooth and nail for rulings in one direction or another. In the course of a discussion if someone says he doesn't support some aspect of gay rights, takes what some call the Cosby approach to black culture, politics and education (explaining it would take a long), or other big issues, or heck even says something in the opposite direction like expressing a support for gun control, that can generate negativity and of course if it shows up on Valve's radar someone is going to wind up with more expensive games. What's more some of this stuff might creep in from sites unrelated or only partially rated to gaming... but affect what people say IN a game because they recognize someone's handle or whatever.
Then of course there is the issue of what's REALLY good for the company in question, see what a business wants is traffic. Someone who raises contreversial issues well causes comments and dialogue, gets people posting, and/or has them stick around. Heck, I'll even say someone who pushes buttons for the lulz and is constantly a deliverably offensive joker is a boon, a good troll is worth a thousand regular users because he gets people to post, and to keep looking at the site/message channel/etc... just so people can listen to him to share in the lulz (knowing it's a troll) or to be sure they can respond with appropriate outrage. I don't fit int his catagory, but I've known plenty of people who do, and honestly I think Valve's system doesn't account for that on top of everything else. People might not want to admit it, but a pack of Care Bears having a picnic saying "this is great" and always in constant agreement, or at least polite, tends to lead to very little traffic overall.
To put it bluntly haters, contrarians, opposers, or whatever are the lifesblood of the internet. Especially when it comes to business, after all whether they decide to listen or not, wise companies at least know enough to make pretensions of caring what the fans think and opening the doors to hear feedback about what should be changed. 99% of the traffic out there related to products is negative because saying "I liked this" and someone else saying "yep" doesn't give much information or generate traffic. Heck, I think that's pretty much covered by the equivilent of a Facebook "like" button.
What's more developers ignore this kind of feedback at their own risk. I look at "Dragon Age 2" and the critical panning it received from users, even if professional paid reviewers stuck by it. How would things have played out if Bioware had decided to listen to it's users, pushed the game up six months to a year and given the fans what they wanted in the way of a deeper character creation system instead of being handed "Hawke is a human" character which when they inquired about it got an overwhelmingly negative response... and yeah, I think Bioware ASKING and then lying about the results and doing what they wanted to anyway influanced what people thought of the game along with all of the other things that irked people (mobs spawning in waves, constantly re-used enviroments, spiders the size of elephants appearing in then air, guys in plate mail jumping out of the sky like ninjas, etc...). "Saint's Row 2" demonstrated how you can have more than one voice track for the protaganist of a story as well. Quashing negativity by charging those who become unpopular for being honest (especially when it's a matter of a company throwing a 4-year old tantrum over hearing things they don't like) is actually going to have a negative influance on the industry as a whole as well.
While I suppose this will raise all my game prices, I'll just say that all my various rambling thoughts (which go beyond what I've said above) make me think that perhaps Gabe is getting too full of himself. "Critical Miss" did a very funny strip about the "God Emperor Of Steam" because along with a valid point about dependency and what would happen to people's games if it ever did go down, it also portrayed Bobby in a rather funny light which was amusing because it was so absurd and out of character from what we've seen. Yet right now, this kind of logic seems very much like the ego trip of someone who wants to play king. Bobby pretty much figuring he's got users by the wrinklies due to all the money they have already invested in Steam (so it's not like they can just up and leave) so he figures he and his people can take the royal position of subjectively granting favor and disfavor. Once he has that, it's only one step from the guys running Valve to demand people kiss the royal pinky ring, or risk their prices raising. (and yes, that's an old school Colonization referance, albiet if you do kiss it in the game your prices rise, if you don't kiss it, it kicks off a revolution).
However, by all means, if Valve DOES decide to make this official policy, please have Gabe annouce it in person, on video, and have him wear an Ozymandias costume, or dress like Emperor Papaltine (I prefer the former as it's become traditional due to the comic strip). Given the amount of money I've invested in Steam already despite my dislike of digital technology I'm doubtlessly going to wind up bowing my head and falling to one knee, but I
at least want something to Lol about in exchange for when I change my handle outside of STEAM and begin organizing the rebellion.... oh wait, I didn't say that, I meant keep my handle and scream the praises of God Emperor Kotick to the 4 corners of the internet, that ring with a little flower on it? A pimpernel, just jewlery I assure you.