-Relics like ARR/HW/SB 
A relic is grind. Ok. But... are we obliged to see it locked that way behind walls and RNG as it is?
Books was not a bad idea but... Khloe or ARR relic book are the same problem : forced content. Challenge log or roulette are not that bad as alternative. Easier content could still give light even if it is less. Roulette is already supposed to lead to random raid/dungeon. Doing roulette could be a slow but possible way do do it (and have somewhat -from my point of view- more meaning).
The real point is here : the problem is not griding, it is "forced/locked content".
Atma and relic behind Eureka are the worst to me.
Relic is supposed to be the final weapon both the one with which we will fight and the one with which we grew. Wouldn't a relic have more meaning if we can start it at 70 and grow with it through our fights? Relic behind Eureka rather than MSQ/roulettes, isn't that weird?
Couldn't be a way of weapon fusion (after all we will use several weapons)?
NB : These are juste afterthoughts