The idea that a good RPG is subjective, so we shouldn't bother trying to change anything, is how we get piss poor rules sets.
The idea that it is not subjective is how we get edition wars.
You can look at things and say, "that's not as good as it can be, and here's how", because you have defined what "good" is for that facet. Do you want to claim that the process of defining "good" is not subjective? That what is good for you is good for everyone else, too, and they just haven't realized it yet?
Each game is designed to produce some particular experience in play. Even the "generic" systems have a "feel" to them. There is, simply put, a design goal, stated or not. Now, we could say that any particular element, or group of elements, is "good" if it meets or assists the design goal. But, whether that goal is itself worthwhile is subjective.
I will analogize: The movie "Sin City", was, in a technical sense, "good". There was craftsmanship in that production, on all levels - writing, acting, effects, everything. It set out to have a particular effect on the viewer, and it achieved that goal. No question. The skill of everyone involved is evident.
However, I still question whether I'd prefer to have stomach flu rather than watch it again. The place that movie went was not a place I wanted to be. I think my life is a little *worse* for having seen that movie. So, for me, technical values be darned, I don't call it a, "good movie". I have friends who loved it, though. I don't think less of them, because they aren't me, and have different needs and wants than I do. The world would be a pretty darned boring place if everyone liked the same things I do. I am happy that there's stuff out there for them. But don't expect me to like it.
That's the issue at hand. Technically successful is not equivalent to "good".