I know what you mean, I took a while to adjust back, but it was riding with a racer that got me back into gears properly.
I think it's easy to be lazy about gears, which isn't helped if they're not working properly.
I also notice that some see gears a the 'enemy' or a challenge. By that I mean some will refuse to use another gear to help them and continue to press on inefficiently.
Gears really are there to help you. An easier gear is a better option than death by lactic or even walking. And what can beat a big gear when the winds behind you, the trail points down and you want to press on.
I fully understand the whole singlespeed thing, been there, but you can't escape the logic of gears.
I also suspect that I'll be pointed towards riders winning on singlespeeds, but without being rude these riders do tend to be big fish in little ponds.
At the top end of the sport gears are king.
I'm not in anyway knocking singlespeed, I'd go back in an instant if I wasn't racing.
What I would say though is if you are riding everything on a singlespeed try putting a smaller closer ratio cassette on the geared bike. That gets rid of the horrible 'lag' in between changes. Using a road block is like driving an automatic as the gear changes are so smooth.