I think it's important to remember that the convention's attended has literally doubled since 2010. So, it's just a fact that it is harder to fit an infinite amount of people into each event.
I made the mistake this year of assuming a free seminar wasn't a big deal and I didn't necessarily need to have it on my list of events. For those, you used to just be able to walk in without people even asking for a ticket. But, no, it "sold out" in the first hour. My mistake.
Asking things like "whose idea was this?" implies you are looking for someone to blame. Space is limited. Try to get in without a ticket. Good luck.