I've been doing this for many years... more than just at long stop lights. If I know I'm going to be stopped for more than ~10-15 seconds, and it's safe to shut off (no risk of rear collision), I do it in my car.
I've never worn out a starter, and the city fuel savings is significant: roughly 5-10% depending on your route/conditions & how often you turn off. Which is why auto stop/start is appearing on more and more new cars each year. It's already common in Europe/Japan (the Euro Micra has it).
In some countries (Switzerland comes up in searching) it's law to manually shut off the engine when stopped at traffic lights if you don't have stop/start. (The light warns you when it's about to change back to green so you have time to re-start and shift into gear).
Warm starts cause negligible wear to the engine itself. Yhe starts that hurt an engine are the cold ones, where the oil is cold, pressure is low and oil has drained away from moving parts.
Of literally thousands of ecodriving/ecomodding forum members who use this technique, I only know of one report of a worn out starter, and he was the most hard-core of them all.
So I would say do it, and don't worry about it. Enjoy the fuel savings. Also, with your automatic, you can just pop the shift lever into N (no button-press and no looking required), and pop it backward into D (no button required) when you do your stop/re-start.
View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...