But maybe there are so many NPCs around that it could be very frustrating to have to speak to them all or to remember who it was that gave the quest.
But that's what the journal or logbook feature is for.

Instead of the generic symbols that do somewhat spoil immersion, why not have the name of the NPC pop up when you 'target' them (there's no cursor, but surely there's some 'dot' or indicator to show you where you are aiming). Between knowing the name of each NPC you encounter and having a physical log of your quests and quest-givers, this should eliminate the need for the symbols from Sacred, DSII, Titan Quest, etc.
Oh please no quest arrows on the compass! They're impossible to ignore and detract from the exploration of the game world. Fog of war on the map will likely be an option, I'd guess. I would leave it on and perhaps switch it off every now and then to 'cheat' and see where things and places are.
As Alrik said these features can be helpful and aren't necessarily bad as long they can be switched on and off.