First, responsible, courteous riders can ride and wear whatever they want in my book. They can pedal or not. Remember, every throttle-only or ghost-pedaling utility rider is a car not on the road.
As for spandex, I've come to see it as a very sensible choice and wear it now on every fitness ride — which most of my rides seem to turn into these days.
Won't bore you with my circuitous and reluctant route to spandex. Real-life benefits in my case:
1. Butt's no longer a ride-limiting factor, and pant seats no longer snag on my saddle nose when starting out.
2. Most of the year here, legs and especially knees work noticeably better when kept warm in tights, and there's never any restriction of motion.
3. A long-sleeved, quarter-zip jersey offers the most flexible temperature control I've found for this climate — which varies not just day to day, but also hour to hour and mile to mile.
4. Those 3 rear jersey pockets hold a lot of stuff. And that lets me minimize the accessory weight on my lightweight fitness ebike.
5. Air resistance is a formidable adversary above 5-10 mph. Streamlined clothing can noticeably reduce it.
6. High-vis tops and socks against black bottoms add a measure of traffic safety.
Bottom line: The roadies can't be wrong about everything.