It isn't "mandatory", because if it were, then the consoles would be targeting that, and they won't be. Just like every generation since going HD the consoles will target 30fps so they can try to push more pixels than ever before. Now not only will they be trying to display new, or demanding graphical techniques, they will also try targeting a native 4K on top of that. I don't really see this cycle breaking anytime soon either. Certain developers can target 60fps for their games if they want, but it's not a system wide mandate. You can't sell frame rates in commercials.
Consoles were never the place to look to get 60fps or higher anyway since at least gen 7. Having said that, it's hard for me to comprehend someone not being able to tell the difference between 30fps and 60fps. Even if you can't "see" it, you can definitely feel it, especially after you've acclimated to playing at a higher frame rate and then cut it in half.