...Yet, many groups approach encounters with the same mindset from 3e or other previous editions - "You open the door, there is a large trol;, roll init and then beat on the troll with pointy sticks and spells until it's dead." Now, I'm not saying there is anything wrong with that, at all. 3e was designed around this kind of combat...
In all honesty, I never once encountered this kind of mindset amongst my players while playing 3e - and I've DMed quite a number of groups over the years. And I don't think 3e was designed simply as a war of attrition, as you suggest. Sure, every edition of D&D has been a war of attrition to war extent (hit points exemplify that), but every edition of D&D has tried to add more combat options in it. 3e had bull rush, disarm, AofO, Overrun, Sunder - just to name a few. And 3e did put emphasis on the need to move, hence the diagrams in the PHB and DMG showing mins cutting across terrain, etc.
Now, I will agree that 4e has put even further emphasis on movement and additional type of actions, but to state that 3e was simply designed around hitting things and hurling spells in not entirely accurate.
In my 3e games we had people using cover, aiding others, getting into good positions, trying to back enemies into a corner, using the terrain, etc. - rarely, if ever, did they ever stand still and hack away at a monster. And the same went for the monsters. If a DM is just having a monster stand in the one spot and simply do the same thing over and over again, then, but sorry, that's the sign of a reasonably lazy DM...unless, of course, the monster in question is as thick as a piece of wood.
You could argue that ALL editions of D&D (or any other fantasy rpg for that matter) is all about hitting stuff until it dies...and 4e is no exception. It's just that with 4e there is a more obvious emphasis on using different methods and actions to do it.