In most instances, a food critic EATS the food, before giving a review. A movie critic VIEWS the movie, before giving a review. And a music critic LISTENS to the music, before giving a review.
It would make sense that a game critic would PLAY the game, before passing judgement.
Am I a critic? Am I being paid and are my opinions being published? No. I don't see the need to hold myself to those standards. If I wrote about rpgs for a magazine or something, then your contention would be more appropriate.
A movie critic that didn't SEE the movie has no leg to stand on when reviewing its merits.
But since I'm not a critic, I don't need that. And can still be sufficiently well informed.
For example, I've read reviews of Battlefield Earth. I even had a college professor who was recruited to join the beginnings of the Scientology movement talk about it. I know it's a crappy movie. It's on many "worst movies of all time" lists. Have I seen it? No. Is there a chance that I could watch it and decide that it was great? Yes (albeit a small one). But I still can reasonably state that it's a terrible movie without having seen it. I know enough.
And I know a lot more about the various editions of D&D, even those that I haven't played or DMed myself.
Reading a forum, or a book about a game is definitely NOT the same as actually sitting down to play the game.
I make no claim to that effect. However, it's equally important that playing in one person's game does not extrapolate to other people's games very well. Even if [MENTION=336]D'karr[/MENTION] 's 4e game is great, that doesn't mean that 4e is or is not, nor does it predict what my experience would be (or that of some other person).
How can you make an informed and reasoned judgement of how people "enjoy" it or not? What basis do you have? None.
My assertions are based on theory and anecdotal evidence, like everyone else's on these boards. I am equally qualified to assert that a game has certain qualities (whether it be balance, enjoyability, or something else) as anyone else here. It's all philosophical, what's good and what's not. If you don't think that those opinions have enough support, you are welcome to shun ENWorld (which is full of such judgments) and consult a peer-reviewed academic rpg journal of your choice.