The problem with Asian-style motorbikes in the US is their utter and total lack of power, which becomes the only thing keeping you whole on a US highway. Cars will out-brake you, cars can out-handle you. Even the MSF will counsel you that the best way out of a problem is to accelerate through it. Acceleration shifts the center of gravity back over the rear tire and improves handling. Acceleration allows you to put distance between you and the altercation you're fleeing. Acceleration gives you a direction to go that cars can't - and a 125cc Bajaj can't accelerate. There's a place for low-displacement, low-impact 2-wheeled transport. It makes perfect sense for surface streets. Things get hairy over 40mph, though. I've got a steady gig 45 miles away up a 12-lane blacktop. Could I get there on a 250? Yeah... but I could cross the Alps in an Ultralight, too. Doesn't mean it's the best craft for the job.
I don't mean to imply that small engine bikes are appropriate for highways anywhere, as in my opinion, the mix of engine sizes on highways I've been on in Asia was a major contributor to traffic. Even so, I've seen experienced riders try to jump into the flow of traffic in Viet Nam and I've seen lots of them eat shit because their instinct is to go fast. You can't do that when a truck will undoubtedly make sudden turns on a pothole pocked road, or when another rider is carrying sections of 25ft. steel pipe over his shoulder. You definitely can't do that when a herd of buffalo might wander across the road. Though those things don't happen here, a squid is a squid, even if he's been riding for 22 years. Just because a dude can go forward quickly doesn't mean he can maneuver worth a shit. I've known guys that have ridden Big Bikes forever, who can't negotiate a line of cones because they're just too damn heavy on the throttle and don't know how to ride in a lower gear, much less how to use their handle bars.