First-come-first-serve has issues:
1. Where do you put the thousands of people showing up earlier and earlier to beat out one another? What if that crowd is keeping the gondola from being unloaded? If you hold them in the park... what do you do with several thousand people in the park and not open any attractions for them? You open early... oops.. no, that would mean not opening at the time as advertised, and that would by lying. And guests would just show up even earlier the next day.
2. 8-10 hour lines are fun to boast about, but they're a nightmare for guests... and for ops as they now have to manage that huge herd. Bathroom breaks, line-cutting and the ensuing fights, the need to get food and water to them so as not to have them pass out (for some folk).
3. You're basically saying, "Hey kids, this ain't for you. It's for the adult nerds who can set up a base camp for eight hours." One may not like the part of the mantra "more family friendly"... but that is a significant part of Disney's bread and butter. So, this system excludes families with kids. "First to the gate" is fair... for people hardy enough to endure it.
I still think a lottery is the way to go...