To clarify, unless I'm driving aggressively, there's no need for me to rev match or downshift, so just come to a slow, take it out of gear and wait for the light to turn after sipping. If stop sign, then into second after the same process. Why work harder? Unless I'm on a hill... That's a whole other subject.
So, there's not really one answer for must of the situations, but from a pure stopping at red lights scenario where most people encounter everyday, why downshift and shock your drive train?
Unless you're driving a truck or something (as in, something with a big torquey engine and a sometimes-mostly-useless short first gear)...quit rolling stop signs.
Learning to stop for first will save you money around here. Local cops like 'four way stop traps' even more than they do speedtraps.
I literally always stop for first. People think I'm a bit odd sometimes when I'm, say, rolling up a steep parking lot entrance after slowing way down for a decent bump between the road and the lot. I'll trade any remaining momentum for a brief pause to shift into first. Looks a little strange, but not all that different from people who roll into the same lots at idle in an auto, then stop as the load from the hill puts their torque converter in that 'neutral' state where it's transferring just enough power to fight gravity and keep the vehicle from rolling back. Then they awkwardly gas it and jerk forward as the converter suddenly hits stall.
The average auto driver, of course, probably knows none of this, he just hits the pedals that makey car worky. Which is why I think people should at least be required to learn how to drive a manual, if not drive one every day. You will be more attentive, and you WILL learn to drive it smoothly if forced to do it enough. Whereas someone who only drives autos (just talking about your worst cases here) may go through decades of driving while maintaining complete disconnection from the car, and never really developing driving 'skills.' They're 100% habit. I've certainly gotten way-the-hell-better at actual driving skills (not always...'good driver' skills...but 'car control' essentially) over the years. And always owning manuals past ~19 or so really helped a lot of that.
Maybe it's just that some will never push their car even halfway to the limits of handling or acceleration (braking...yeah, they get that one sometimes). So, okay, final verdict: I say, mandatory road racing course in 'reasonably priced car' sort of vehicle. Something like Top Gear's current Kia, which is similar to the newer Fortes and Elantras (read, very competent handling with a decent enough level of power).
Obtaining your license requires a certain lap time. For those unable to achieve the time needed (but are somewhat close), restricted licenses can be issued. They will be known as 'teenage girl/old person/Asian' licenses (hey, I know, I'm offended to, but people will create these terms; it's out of my control...).
Learning to go fast would keep people safer. This is my paradoxical stance and I'm stickin' to it.
/derail (let's face it, 'do I coast in neutral' was pretty much done, all that anyone else is gonna go is argue about silly downshifting for stops ;P)