These procedures trade my freedom and privacy for security.
I always have someone keep an eye on my stuff, but I've also been at similar events (Chaos Communication Camp 2011) where keeping something unattended was not a problem at all.
Treating all you attendees like potential thieves is simply a bad premise for a hacker event.
Yes. Of course. And there have been or will be stolen laptops at this event. The "security system" is easy to circumvent, if you do a little planning and want to steal something. The stickers are removable and re-attachable. You can register whatever, whenever you want. It is not done at the door. On my MacBook the serial number was taken from a screen, that I prepared.
But even the CCC had several years of congress with this kind of "security". So I am not mad at the organizers. We even had one congress where every participant had his/her photo taken. This actually had a major uproar and wasn't done ever again. I think maybe the organizers will learn and do things differently next time. At least I hope if they do this again in Berlin.
The most ridiculous things like not bringing lighters or no smoking outside the Hanger was removed from the Term & Conditions.
Treating all you attendees like potential thieves is simply a bad premise for a hacker event.