The rewards should still be adjusted a bit. Finding plasteel or diamantine is so easy and you get way more weekly-coins doing so than getting some while e.g. finishing 8 missions.
It´s not just harder to do on higher difficulties, which also grant way more plasteel / diamantine to finish them in 2-3 runs, they take way longer.
I do get that it´ll take longer for poeple running malice or uprising to get such stuff done, but it´s not really balanced out.