The NES and Sega Master System have a ton of fun and engaging games. Both systems have controllers with only a d-pad and two buttons. The Playdate adds a crank and accelerometer.
I agree you don't need a slew of buttons for a good game, but a lot of that design space has been explored already. I've seen some clips of the games in action, and it doesn't look like anyone is really using the crank or accelerometer in fun enough ways (after all, accelerometers have been on AAA console controllers for a while now and are relatively underutilized). I know this is subjective though :)