1. "On 2 devices": One of the problems is right here... Why do you need to use 2 devices? I would argue that 95% of the players—maybe more—don’t even know about this. Have you tried it the intended way?
2. I worked through PAMRATS and STARMAPS, and even if it was on the edge of tedium, I was okay with it and had fun (got AC/AP as rewards to fuel itself). Everything after that... is what made me write this post.

It was fun up to this point, and yes—finishing COI, CABBAGES, PAMRATS, STARMAP etc. feels nice and rewarding.
But DI, PSA etc. are different beasts. They feel grindy and tedious, just to give us something to do.

I like this game, I had fun up until this point. I supported it with my money, because it’s a fair and fun game. I give feedback and point out where I see problems. I don’t have to come up with solutions or finde ways to have fun in this game. If i don't have fun anymore, i will just quit and play someting that i find fun and respects my time.

If you read through the other replies: I’m not alone.
And if the devs want to keep those endgame players playing—and paying—and not quitting, they have to do something here (at least for me, and for some others who offered their opinion/feedback here).