Like Bowsette said, many, many things. My number one would also be accessibility options, but since that's already been so well articulated, I'm going to go with performance settings and the option to change control bindings. I'll take stability in equal parts framerate and resolution over one or the other being inconsistent any day of the week. I would have preferred, for example, to have been able to lock Breath of the Wild's framerate to 30 and resolution to 720 than to have it generally stay at the bizarre number of 920p and occasionally drop below 20 fps. I don't need much in the way of graphics or performance, just stability. On the other note, it's kind of pathetic that Breath of the Wild doesn't let you rebind the controls, either. I like the new controls, but I think I might have preferred to keep the classic Zelda style (sword on . I would have at least liked the option to try that for myself. Nintendo's excuse for not including it was absolutely pathetic, too.
Sort of relevant, but most graphically intensive games for the Xbox One and PS4 do use dynamic resolution scaling to maintain a consistent frame rate. I'm not sure if Breath of the Wild does, but I know that games like Doom 4 and Wolfenstein 2 on the Switch do so.
Also, yeh. Not being able to rebind controls is a cardinal sin of the gaming world.