Actually, the 21+ event, specifically the Karaoke bar on the 23rd floor was one of the few highlights for me and my many 21+ and over friends. As members of the "con scene" for many years, this was a nice segway from the standard con schedule, especially for those of us who enjoyed having a place that suited an older set of fans. I was also a vendor at KUM and although we did well in sales, the logistics were very upsetting. Or rather, the lack of logistical organization.
Anyway, back to topic:
Although I can understand the consternation of those under 21, I really appreciated having an event that catered to older fans, where we could relax, have a drink if we wanted to, and have access to a different atmosphere. Anime convention lounge, what have you. The staff both KUM and Hotel were wonderful and treated us like adults. The view was amazing and the ambience was laid back but fun.
For those who have not attended conventions for very long, it may be harder to understand.It is getting to the point where convention attendees are aging and therefore some tastes are, too. This was just the kind of event many of us old con fogies look forward to, away from the standard running and screaming of attendee fans. It's amazing how seeing/hearing that novelty wears off very quickly. By having events catered to the older fan base, a convention is showing that it understands it must also grow and evolve in order to maintain returning attendees.