Many who attend the San Diego Comic Con complain about the ever changing experience of it. Notable long time attendees like Mile High Comics do not attend anymore largely because of the expense and the crowded venue, these and other factors drive down revenue and make the show seem less attractive (we have this same issue in our neck of the hobby woods).
The show has become far more main stream and is building itself around the powerhouse movies coming out of comic book and fan/geek world (like the Walking Dead). Its the place to premier now.
Which is cool.
But it apparently detracts.
Here's a good article on some simple fixes, all sound very reasonable to do.