They outgrew the last location (The MEC) because during the friday there are a lot of buinesses still working. They probably got complaints over the years. The GSEC is slightly larger and there are other buildings available for use. This year however the building management decided to screw over AnimeNEXT and take away the "300" building at the last minute from what I've heard. So I guess the GSEC management is now on not-so-friendly terms with AnimeNEXT now.
Given than the only other places that can house the convention is Atlantic City, Phildelphia or NYC. None of which this con could ever afford or organize. And all the other NJ Convention centers aren't as accessible. They're kinda stuck here. Or they have to implement attendance caps which no event ever wants to do.
That said. I haven't been to a con this size ever before and everyone pretty much out of costume and doing nothing by 10PM on Saturday. Sure there was a dance thing. But usually that's "full" and people spilling out for a long time. But I didn't hear it this time.