Well they don't want to pressure people to play that much. The game is very much that you can just not really play for 3 months then come back, clear extreme, unreal, prog some savage, progress your relic step and queue pvp once a day for 1 month just to catch up on the patch content.

They do add grinds for people who want them, such as for mounts or relic weapon steps. But as we know, when relic steps take even a tiny little bit of time to grind FATEs, the forum gets filled with complaints about how it takes them more than a day to farm FATEs and CEs. Imagine how much they'd complain about your suggestion?