I think there are two issues here:
First of all, pilots need to have a huge degree of control when things go wrong. Take the combined fuel tanks for example - there's no reason they couldn't be connected together with a pipe and some baffles, until you get airborne and discover that you've got a bad batch of fuel in the left tank.... suddenly you wish they weren't connected together any more.
But the most important thing, I'm sure, is pilots' egos - the more knobs we have to play with in the cockpit, the more important we feel!
I know I miss the mixture and carb-heat controls on my Rotax - it's just boring being able to control the engine with just one lever! (Oh, plus the mag switches, and fuel selector, and choke, and prop pitch!)
FFF
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