The other night I got into a discussion with a nerd friend of mine about what might be the best keyboard ever. We agreed that it should give auditory and tactile feedback. It ought to need little force, but also enough to make it sure that miskeying was unlikely. She even agreed to a point with my idea that the classical grand piano's touch could have something to do with a good keyboard touch, but I think I sort of lost her about there with the consequences. Thus, I'll dump the whole of my reasoning here.
A proper keyboard needs to have both tactile and auditory feedback. Those two modalities work together well when you're inputing information that will be interpreted by your visual sense -- the segregation of the two modalities heightens both at the same time. Your tactile sense helps you keep track of the keys, your auditory sense provides exceedingly time-accurate feedback at the same time, and all of that is separate from your visual sense which serves to check and guide the overall picture of what was said. Given that our hearing is accurate downto the microseconds, it probably makes sense that the primary auditory feedback should be purely mechanical as well, since the roundabout through a computer would introduce a delay and a temporal uncertainty that is far worse.
Thus they keyboard should be quiet, but it should nevertheless sound/click.
Then, one of the worst things a keyboard can do is to require lifting your fingers off it. To any touchtypist, that sort of thing seems like a swamp that swallows your fingers. Thankfully that sort of thing is rare today.
Third, it's also rather tiresome to have to push down the keys against a viscous, dissipative load, plus a string force. The string force which negates the previous need to explicitly lift your fingers off, but at the same time necessitates quite a lot of force to be used on your part for every downward keypress. And since laptops derive the balancing force from a nonlinear and viscously damped rubber pad, any work you expend on the key in either direction is rapidly dissipated. This is already a workable balance, but not an enjoyable one, and it's what laptop keyboards pretty much always do.
Fourth, older keyboards, and the better quality current, full-width keyboards do something quite different. They dissipate the end-of-movement energy via a plastic collision at either end, in average they exhibit linear tension, and then they have a little bit of die-hard hysteresis in the middle when they click. In here, the design parameter was traditionally about where the click happened with respect to the common typing motion. In here, we're finally narrowing downto the proper ergonomics.
But then, fifth, even the company my nerd friend pointed to hasn't really gone beyond this paradigm. They haven't really considered whether the traditional design is the best one; they've just gone with the best that we had in the past.
So the final, sixth, longest point of my is about keyboard idealism. Bear with me here, because this is gonna be wild.
Clearly we can't get all of those different nice aspects in a mechanical keyboard at the same time, unless we resort to very convoluted mechanical designs. Those will then break under no time. So, let's ditch the mechanical design everywhere we can. The plastic, mechanical stops will have to be there, of course, both going up and down. But the rest? Not likely.
Otherwise than that, every key could contain a lightweight, very tighthly wound, fed with very high voltage (from a buck-boost-fed power supply) moving coil. Set in resin, and moving against both a set Neodymiym magnet at the bottom, and a similar set coil further out. With enough current (plus regeneration, plus a big enough reserve capacitor), and especially high enough scanning frequency and proper signal processing, this sort of thing could mimic any and all touchfeels via algorithm. All of the so called "moving parts", i.e. coils, could be set in resin and be totally isolated wrt each other, for automatic military grade assurance of functioning. Pour a bottle of coke on it and it just keeps working, without any stickiness.
Then, it's not just about force or feedback when you work a keyboard to its fullest. Here, my favourite example is the grand piano. Pianists are able to expend even full Watts in steady state on their keyboard. Us touchtypists are not, so we get tired, and our output dropps off as our hands tire. What's the reason? Obviously it is because our power output isn't properly impendance matched to the keyboard, and the current keyboard is such a thoroughly dissipative thing. So why not make the above electromagnetic coupling work both ways, so that every keypress leads to electrical input, and then the circuit recouples that energy right back into the typist's fingers to bounce them off the keyboard? In that way we could go with "staccato typing" with diminished loss of energy, the way pianists do.
Old school electronic circuits could not have done that. They would have incurred heavy losses because of low voltages, too low magnetic fields, and resonant circuits which were only designed for a single resonant frequency/speed of typing. They would have been massive and dissipative as hell, as well. But today, we could easily implement all of this using a movable coil, a fixed coil, and if we wanted to save energy, a fixed high-flux permanent magnet, per key. With high frequency active control and the right power circuits per key. No, it wouldn't be cheap. But yes, it could be military grade in more than one sense, and even in the civil society that sort of thing could save insane amounts of money from treatment in carpal tunnel syndrome, lost productivity due to programmers struggling with their keyboards, and so on.
