Modern technology changes too fast for evolution to catch up. Keyboards haven't been around nearly long enough. Plus, people with long fingers would have to out-survive people with short ones.

Evolution is based upon what 'fits' best for survival; those with characteristics not suited for survival typically die before mating, while those with characteristics which aid their survival grow healthy and make good mating prospects, thereby furthering their genes (and the inherent characteristics which gave them that advantage.) Humans have negated that evolutionary method by ensuring that even those who would not survive do survive by changing their environment rather than allowing genetic characteristics to dictate survival. Many people who are alive would be dead if evolutionary pressures weren't negated by man's technology; eg. the extremely short or long sighted people would not be able to 'hunt' and would die before breeding, etc. Short or long fingers don't appear to be a survival characteristic of survival until mating age; indeed, with today's technology, many things which once were required to survive until mating age are no longer required due to technology (e.g. juvenile diabetes, sickle cell anemia, blindness, and so on.) Therefore our environment no longer places these pressures on us to survive, so even the unfit can survive to breed.

Evolution can only occur is one trait is surviving more than another trait. Therefore, there would have to be some reason that people with short fingers were DYING or otherwise not able to reproduce because of said short fingers. Long fingers would have to be a beneficial trait for survival or attracting a mate. Evolution is not as an intelligent process as you think it is. It is a dumb process that takes millions of years and is extremely gradual. Evolution is simply the "survival of the fittest" concept in the LONG term.

I think humanity has moved past it's physical evolutionary phase. Any further changes done to the the human genome will probably concern mental attributes. So instead of adapting to fit our technology we become the technology.

anything is possible