It should be a challenge to hit that cap for all playstyles (or none I guess).
WHAT!?!
Why should it be a challenge? FDEV literally give free ARX to encourage people to play, but you want to make it so hard to get the ARX people have to play constantly to get them? That's really....well....really strange and entirely negates the point of free ARX, they are a reward for playing, not a grind target which you seem to want to make them! If they were so hard to get that you had to struggle to get them I wouldn't struggle to get them, I would still keep doing exactly what I am doing now, I just wouldn't get 400 free ARX per week. ARX aren't a mechanism to get players to change their playstyle to earn them, ARX are basically a free gift for playing. This is an entirely bizarre interpretation of "FREE" ARX, they stop being free the moment you make them a grind target!
During my entire history of playing I have spent ARX exactly twice, once to get the vintage space suit and once to change my FC, I literally have over 40k ARX in my ARX account and have no intention if spending them, and they were all free. I don't care about free ARX really, all I care about is playing the game, it's the OP who wants the game changed so they can get free ARX for doing nothing. The fact my playstyle just happens to earn me 400 free ARX per week us a coincidence at the moment, when I was working on the HIP project sometimes I was so far out on the fringes and stars were so sparse I couldn't actually earn 400 ARX per week, and you know, that didn't bother me at all, funny that!