I love the fact that there's no respawning of enemies!
First, it's totally neccesary or the XP debt from mindreading will be totally useless... It puts you in a hard position, makes you not want to waste a mindread.
Then secondly... It's what makes this world more alive than any other world, you kill some mobs for some NPC's and they're actually gone, forever. You go through an area and poof you really 'cleared' the area. Totally awsome to walk through the environment when you got rid of the villains and everything is nice and quite. That gave a great feeling of satisfaction
Although I do admit, one mob randomly here and there wouldn't really hurt that much but still overall... I think it's a pleasant thing.
It baffled me at first as well, but there's some unique things in this game that I began to appreciate after a while, I wouldn't go as far as saying they 'reinvented' the genre, but some things are a bit different and some things are somewhat oldskool