Maybe tie the patent duration to some measure of how long the invention took to develop? An algorithm that took a day from napkin to filing for the patent? You get a day of protection. A drug that took 10 years to develop? You get 10 years.

The difficulty there preventing companies from exaggerating about the time it took to develop. I suppose it's not too much to ask companies to show written evidence of the date that a specific invention process commenced.