As far as I know 190 was the only aircraft that had auto mixture. Perhaps it was a post war mod?
I've never had to adjust the mixture on the P-51D in Il-2 sturmovik, and the same goes for a lot of late-war American aircraft. None of the Bf 109E-Ks had mixture controls, either, but many aircraft did have manual mixture controls. I don't find it to be too much of a pain because it's very obvious when you need to adjust it, and there's no aircraft-specific knowledge you need to do it right.
The control that actually makes you know your aircraft is the manual blower. For example, the F4F has 3 stages, and if you don't know the right altitudes for them, you'll have a hard time escaping from an A6M when you need to.
Another one that affects combat performance a lot is cooling systems. Opening radiators and cowl flaps causes drag, and the slower you're going, the more you need to open them. Some aircraft had automatic radiator controls, but someone who knows his aircraft can get more from it with manual control. This was tested to death by P-51D pilots in Il-2 Sturmovik, and they found that the fastest sustainable settings were 95% throttle, 95% prop pitch, and the radiator closed. You can run like that indefinitely and you'll be damn fast; just don't get slow in a turn fight.