I'm fine with the early starting times around here. I attend hamfests mainly to buy or sell. Its not a 5-6 hour social event for me to talk to everyone. I can stick around for 1-3 hours and leave early enough to enjoy the rest of my day doing whatever. Getting back to the original post, I've been at the South Milwaukee fest for decades. There are plenty of times its on sunny hot humid days. Starting early allows some comfort before things get real uncomfortable. The only shade is your shadow unless you set up a tent. Early start times is a natural thing here. Its the late risers that seem out of place.
This AWA event is held in a hotel parking lot - there's no way the Nearfest approach would work without cars and people crashing into each other, There's no "bad will" created - folks are perfectly happy with it and it really is a fun technique.
One of my local clubs changed the swap meet start time to 9AM, with no selling before that time. Other than some pre-arranged deals, the sellers seem to abide by that policy. Changing the meet to 9AM has grealy increased attendance as guys who live 2 hours away are more likely to attend, since they can arrive before the start and don't have to wake up at 4AM! Even starting at 9, the meets are generally wrapped up by noon.
Don't mind the early start time for hamfests. I like to get in early to look for bargains and be on my way most times by 9:00-10:00 AM depends on the size. I can cover most in this area if I get up at 5:00-5:30 not crazy about being an early riser, but it's not every day.