On the contrary, it was totally terrible
They might as well add a button for “add mana for gold” in fights, both in D2/R and D4 and get the same effect 
No offense, if anything was terrible in D2 it was exactly that, never in one gameplay’s cycle was anyone forced to go auto or take care of economy to preserve power for the right moment/s usage
Instead it was more gold than mana pots every single time and whoohoo, never in crisis for power… IDK about you but that sounds like playing an FPS you have unlimited ammo, really bad design IMO, perhaps some might like it but think there’s a bit of unrealistic view to call it a positive feature
Perhaps the Generator/Spender doesn’t work, or doesn’t work as intended, but one thing is certain - definitely the D2 system didn’t