Why? It's how patents always have worked. And even with a maximum of 20 years for patents they are more often used to stifle innovation rather than encourage it.
Copyright and patents should start at 5 years, and then be possible to extend 5 years at a time up to 20 years if the company owning the copyright or patent can prove it's still in active use and not only used to prevent others from moving forward.
It never is, but it prevents them from continuing to build new planes were profit has priority over security and "accidentally" killing 100s of people