Just because you hate a park chain doesn't mean that everyone thinks the same way that you do. While I don't like everything that goes on, I think your assesment is unfair and biased. As an employee at Valleyfair, I can attest to the fact that most of the GP likes at least Valleyfair. (and I would say that it would be the same way at most, if not all CF parks) If the GP didn't like CF parks, they wouldn't go to them, they would find something else to do.
I haven't experienced the season pass system, but I believe that anyone with a season pass can go through the main gates at Valleyfair, I'm not sure if its the same at all the other parks yet.
While there are some employees that poorly interact with guests, I have noticed from comparing Valleyfair to other places that hire low wage workers, that the customer service seems to be much better than those places.
There are some rough rides, but honestly, I think that most rides are well maintained. I can't comment on any six flags or other CF parks, but I would think that most parks aren't much different in this regard.
Charm is a subjective term. What do you describe as charm? Lack of trees at parks? Old attractions being removed that may cost too much to maintain to justify being open? IMHO, most of the GP don't care if the park keeps it's classic rides or if it has trees/good scenery (If they wanted that, they would have paid to go to Disneyland, not a CF or a SF park. Are you going to say a mall doesn't have any charm just because it doesn't have enough trees?
The reason CF is doing well is because they usually balance the attractions enough so that there is something for everyone to do. They also don't spend more than is wise to spend, unlike SF did.