I guess what Lego should do, is make the sets that are SDCC exclusives just variants of sets that would later be available to everyone. Like if the Batmobile set would be released later this year, but the SDCC version had exclusive minifig variants or a special plaque that said SDCC 2014 or something. That way it's just a collectible variant and not an ENTIRE SET that nobody else can get.
Same with Minifigs. Like someone else said, make a SDCC variant of a fig, not an entire fig only available to people at SDCC 2014. Collector goes in a set, but Rocket Raccoon gets a variant. I think that would take the sting off a little, yeah?
Edit: like, POP! with their little statues they make. They made a Mr Incredible that's available to everyone, but for SDCC a few years back they made Mr Incredible in his retro blue outfit. So it's not like ONLY people who went to SDCC got Mr Incredible, they just got a rare re-color.