I'm in the Open registration category this year because I didn't go last year. Had I known this was going to happen, I would have bought a single day pass I wasn't going to use just to be able to get in before everything gets sold out.
If ticket sales are anything like the previous 2 years, there's going to be a lot of people with split day badges (Thursday/Sunday and MAAAAAAAYBE Friday) and tickets for the Saturday show will just about sell out during pre-registration. This sucks especially for people who won't be able to pick up their badges early (SDCC Policy makes it especially difficult to get a single day badge more than 24 hours in advance), be forced to wait in the horrid "badge-for-conformation-paperwork swap" lines just to get in, and will most likely miss out on panels that happen before noon. And forget about getting into Hall H before 4pm.
I don't know (other than the cash grab) why they decided to eliminate the 4 day with preview night badge option. Only the most hardcore of hardcore were buying them, and those folks genuinely WANT to be there the whole time. Most of those people are spending the whole weekend in town, and turning it into a summer vacation. Plus it was a single trip through the registration line and you were golden the rest of the weekend. I can't imagine how terrible it is going to be to stand outside in July weather, fully costumed, for 2+ hours while you wait your turn for your single day-pass.
In addition, since SDCC has said you'll have to keep this years badges for pre-registration NEXT year, will you have to use them individually to get the same days as you got the previous year? Will you only be able to pre-buy the days you got and hope you can get the remaining days during the open registration? Think about it...If everyone who gets a single day badge this year pre-registers for next year, then there aren't going to be any tickets for anyone else outside this same years show, and those who do pre-register will be able to buy days they didn't get the year before, thus eliminating MORE open registration options for people who just want to come see what all the hype is about.
I don't at all understand what SDCC's endgame is here. They are setting themselves up for serious blow-back from the very same people who made them as big as they are.