Why keyswitches for mechanical keyboards are just switches?
Nearly everyone wants to put them in a matrix arrangement, with diodes. I'd expect that including the diode in the keyswitch would cost less than, say, twice the unit cost of a diode, so less than ten cents. The cost of a keyswitch is in the ballpark of 1$, and I expect switches with diodes to be preferred by a lot by many people.
In fact, why not go further? Padauk MCUs cost ~5c each: we could then add one to each keyswitch and have them be addressable. That would make wiring the keyboard up much simpler (you just wire these 3 wires to all the switches in parallel).
Is there a reason why one can't buy such switches? I've only found references to some ancient (and thus rare) switches that had a diode built in, but nothing that can be actually bought for a sane price in quantity of ~100.