[MENTION=435212]SamSpade1941[/MENTION], 30 years ago, people said the same thing you're saying, that clinchers had improved so there wasn't much point in riding tubulars. So the argument for clinchers should be even greater now that they've improved so much. Still, some ride tubulars.

I think reduced weight of tires and rims is probably the biggest. Some say the feel of tubulars is best, and I'll bet the biggest contributor to that feel is weight.

Oddly enough, even though repairing a puncture is complicated, and even though mounting a tire properly is involved, changing a flat on the road is actually easier and faster. You don't need a lever. You just pull the tire off and put your spare on without using glue. At least that's what I did when I rode tubulars long ago. In theory, the risk of rolling a tire off is greater when you don't apply new glue is increased, but I never rolled a tire. If you change a front flat, you really should ride carefully.