Unfortunately, the cons have become a machine, an industry. It was already getting bad in the 80s when I used to go, but it clearly is 10x worse now.
What was so bad back in the 80s? The cons I was going to back then, they didn't even charge for autographs, and I can remember hanging out with the guests at room parties back then.
What made me feel that things were on a downward slide even in the early to mid 80s were two things:
The admission price kept going up and up. For a kid who had to beg my parents for money, it was not fun to see the price creep up to the level you'd normally pay to go to a rock concert when the vast majority of the experience was just walking around the exhibit floor so you can spend MORE money on merchandise.
2) The promoters!
Yes, I think the promoters are the source of turning this into a racket. The guys who ran these shows used to come out and introduce the guests, and the spiel they used to give always made me uneasy. The promoters sit between the fans and the celebrities. I know there are logistics to putting on these shows, but I felt there was something exploitive going on back then and it's only grown since then. Access to celebrities has become a valuable commodity. Conventions used to be a place for Hollywood types to petition the public to support their shows. That's what Majel Barrett was doing when she appeared--plugging TNG before it aired. And she did it with a healthy dose of humility, that she NEEDED grass-roots support. Also, George Takei was warning the public about the plans for rebooting Trek the first time they had thought about recasting and doing a story about the academy. There was a sense that both sides needed each other, and had reasons to be thankful for each other, that they were both on the same side to fight for quality science-fiction. All that goes up in smoke when the actors use the convention circuit like an ATM.
There definitely is a greater sense of "performance" than there used to be, and I guess if people pay their money they can expect some de-facto standup comedy, and the TNG troupe is amazing at doing that based on what I've seen on Youtube, but once it gets down to the photo-ops and autographs, then it's pure commerce which is not the way it used to be. Buying collectibles at the booths yes, but it was nice and discrete that the cost of an autograph (if you want to wait in line) was folded into the ticket. Handing money a-la-carte over to get someone's autograph is just tacky. I know it's how it is and it's not gonna go back, but I don't like it.