While its true a tach in not required for day to day riding the information they supply can be useful. Detecting or confirming a shift in idle speed, or.perhaps knowing rather than guessing the motor is at the perfect rpm for a dragstrip launch if that's your thing. It's a potential aide in diagnostics as well. Or heck, maybe just the enjoyment of watching the needle sweep across the guage is reason enough to put it on the 'Must have' list. Yeah sure, I've had plenty of bikes without one and it not be a problem but for most of us motorcycles are about wants versus needs anyway. If the man wants a tach he wants a tach! Lol. I mounted an hour meter tach combo to my fuel injected 250 to help keep an eye on idle speed because it starts and runs perfectly only when the idle is set within a fairly narrow 200rpm range. Get outside that range and its tougher to start. So yes, they have their place even on modern bikes.