Compare with musical keyboards where not only key number but also the velocity matters, so each key has two electrical contacts, and the whole thing is usually scanned around 10kHz for proper velocity measurement. Although key contacts are arranged in a diode matrix, the latency is usually below 2 ms, even with good old MIDI.

So neither the keyboard matrix nor the debouncing justify a latency of 10 ms or above.

It is nice to see that latency is an issue in gaming now, similar to realtime audio, where most operating systems are still not very usable - with the exception of OS X.