D2 massively outperforms D3 in terms of player engagement and replay value well pretty much every aspect. Only the combat feels a bit cluncky but thats a year 2000 issue, not surprising D3 does better in that regard.
Clearly they need to have another good look at D2 to make D4 a proper D2 sequel and forget about D3.
D2 remaster would be cool but I doubt it will happen. The suits gonna bet their moneyz on D4