We just returned from a 6-day loop from Edison Lake, with 2 days on the JMT (same as PCT here). We were going north; seems like all the JMT guys were going south, so we passed tons of backpackers. Out of all the hikers (perhaps 30 groups), only one couple looked like they were going "light". We lifted packs on the boat taxi: no light weight hikers here! One JMT hiker was carrying a 5-pound 2-man tent just for himself. I do not think it has rained for a month in the Sierra. Mosquitoes are practically nil right now too. Lots of heavy Nalgene water bottles. Lots of heavy-duty sleeping pads. Lots of 6-pound Gregory packs.
On the positive side, several of those camped at the Vermillion Lodge were going light- a Tarptent single Rainbow tent, a poncho set up, a bivy. So the message is getting out, however slowly. It seems to boil down to personal choice- which is good- we do live in a free country. There is an incredible reluctance go trade campsite creature comforts for all-day walking comfort. And I am far from light myself. I still have about 28-30 pounds on my back starting a 10-day trip.
Being a part of this forum makes us think that everyone is going light. Contrary to our personal interests in going light, it seems to me that most folks are still on the heavy side of the scale. Is this what you have observed in other places?