I don't think the Grind is bad. persay. But more along the lines that the RNG is just a bit unbalanced on certain things.
It feels that when your looking for a certain item, it says that its common but feels like its actually rare or unique instead.
I feel that certain items should be weighted to certain locations, that is that they have a higher chance of being in that location that others. Or perhaps give us hints of what is in the box itself. When we mouse over it, the box could show 2 possible items that it might drop then let us choose to go to another room if its not what we are looking for.
Give a little more player agency on the search part other than, go to room and click on box.
The Luck system is a good step forward away from a grind, but its not addressing the problem of the fact that too many items are avaliable within the chance of selection. Heck one time I swear I got a common item from a rare box.
The rest of the game is fine, its great mechanics and such, its the item chances and stuff which mess with the enjoyment...