Optimized solution to avoid of the keyboard matrix problem.
As for a manufecturers, a good (optimal) solution for that on my sight will be :
Not to do a matrix of keys with diodes, but use a straight and separate contacts, where those contacts have a common ground (so called VSS or VCC; VCC is not counted a ground, I know), thus their state does not need to be scanned, and the controller in the keyboard can either read the state by a single operation or just wait for its change.
In such construction, i8042 becomes unusable, but I don't think this is a big problem; hard to do even an approximate statistic on how much new chips these days are created every day.
Ground contacts need to be output multiple times from the "matrix" (this word in this case slightly becomes irrelevant at this thing, thus name it some other word instead); around one common ground contact per 2-10 keys; that should give optimal relation between cost and quality.
For example : for 100 keys a keyboard should have 10-50 ground contacts.
I think the grounds should better be shortened on the film.
The number of ground contacts can be lowered down to 1 common ground contact per lets say 20 keys.
The idea of separated contacts has appeared for me somewhere at ~2009-11-01.
Used at ... :) - I wonder - when it will be (?)