Tachometer is just an unnecessary bother unless your deaf.
I disagree. While I NEVER use the tach as a shift point guide when I'm getting on it, it IS nice to know where your motor is spinning. Especially at highway speeds on these bikes. When cruising down the interstate, it would be really nice to know just where the motor is at speed wise so you can reassure yourself you don't overheat and lockup the motor. For me, it would be nice to have the Max RPM read back after taking a pass down the 1/4 mile or a run around the dirt track. You can even use a tach to help calculate gear ratios for the crank shaft and counter shaft gear sprockets to obtain your most efficient set up for your needs, whether for torque or speed.
So, no, tachs are not "unnecessary". While not for everybody (and everybody has their own opinion) I have to say that they do have their place.
Scottie