Another good example of a patent restricting innovation was the patent on 3D Printers. That's why in the past few years, 3D printers have become so much more prevalent and accessible (you can buy one for a few hundred dollars today).
These definitely stifle innovation. I'd think a more reasonable approach could be, you have a patent for 15 years (or whatever arbitrary number is reasonable) or until the patent holder makes some multiple dollar amount from things that use whatever is patented.
That is, if it costs a million dollars to develop e-ink screens, the patent is valid until the company has had revenue of 20 million dollars on devices that have e-ink screens. Tying it to revenue instead of profit is intended since profits can be turned into revenue easily to bypass the restriction otherwise.
You could also add a minimum number of years (obviously less than the max mentioned above) so companies have some protection across various metrics.