I wish that someone would develop a great engine for interacting with NPCs. One that would make it just as likely that a wolf would run away and hide from you as it is that it would fly at your throat. One where everything animate could be friendly or neutral as well as hostile (except for the really nasty monsters of course, but they'd be the exception). One where you could negotiate or barter with goblins or bandits perhaps, instead of getting into an unavoidable to-the-death fight. Also, characters would react differently according to what they'd seen you do (a civvy who's seen you hand money to a beggar is going to react very differently than one who's seen you stab the beggar in the throat), what their and your circumstances are, what clothes or armour you wear, etc. Seriously, is it that difficult, given the technology we've got at the moment? If you can make a playable engine like Bioshock's, you can certainly do what I've said above. But nobody ever has yet.
I could imagine a great RPG that could be made like this. It would mean that "personality" as a statistic meant something other than just spellcasting ability, speechcraft could be vital to a stealthy or negotiator-type character, and best play strategy would incorporate lots of non-fighting elements, as well as several actual fighting ones that can't be used effectively when there's really only one tactic that hostile NPCs use - all out offence. (Mastery of the bow for example - in games like Oblivion, the bow is practically useless when every other living thing you're likely to come across anywhere other than on city streets is guaranteed to go for your throat before you've got time to draw it. What if you could use your bow on retreating NPCs, or ones that stay at a distance without attacking? What if NPCs like wolves waited to gang up on you with other nearby wolves before going after you - would you be able to spoil their plans with a well-timed bow shot or throwing dagger? And would killing one wolf with a bow cause others to run away in panic or attack out of rage? What if different wolves reacted differently, randomly or according to how many others were nearby?)
The effect of always hostile NPCs is that only an absolute nitwit would choose to play a "stealth" or "personality" type character over one who's a master at hitting people with swords, summoning demons or spewing high-level fireballs. In 95% of RPGs that I've played, there's practically no point in choosing any character except a high-level wizard or warrior. I put this entirely down to the total lack of intelligence when dealing with non-human characters. Does it have to be this way?