Not having been on the hill 20+ years ago, I can't comment on crowds and behavior now versus then.
The equipment thing cuts both ways. Shaped skis are WAY easier to turn and stay in control with. But that can also give people a false sense of control, or encourage them to push the limits more than the old straight skis. You also often hear better/more extensive grooming and snowmaking brought up as a factor. It's hard to go fast in moguls or crud if you're not really good. On corduroy (or a sheet of ice...) you can really haul if there's some pitch to the hill.
I think the ski/snowboard thing is not very relevant. Inconsiderate intermediate skiers probably tend to go faster than inconsiderate intermediate snowboarders, but I also see lots of snowboarders who can't turn worth a damn, especially on ice, and are probably just as close to being out of control even if their actual speed is lower.
Courtesy and awareness matter a lot more than technique or equipment.