I am currently involved in two DnD games, one of which is using 4th edition and which is an endless series of challenging yet balanced encounters that we defeat by playing nearly optimally with nearly optimally designed characters. We fight mostly groups of 4-6 enemies in well defined dungeon areas and after we lose the expected number of healing surges and daily powers we move onto the next fight with nothing more than "Obviously we loot the room, is there any stuff?" The other group playing Pathfinder is quite the contrast because it involves long sections of roleplaying and decision making which lead to all kinds of strange plans like "Let's go visit the Frozen Sea to the far north and see what is there!" rather than just one more fight. The fights are random and the monsters we face are not neatly organized into appropriate encounters but rather just given an XP value and the DM has to guesstimate what we can beat and what will destroy us.
Clearly the first style caters much more to the mechanics player who wants combat and constant tactical challenges. 4th edition is great for that because the powers and enemies are drastically more predictable and balanced than in Pathfinder. Of course 4th is still heinously unbalanced in many ways but it is worlds ahead of the older versions. Pathfinder also has all kinds of rules for crafting things, making poisons, earning money as a blacksmith and loads of other random stuff that gives mechanics for things that are primarily about roleplaying rather than maximizing combat efficacy. Pathfinder feels more realistic to me in that it is wild and messy and unpredictable - just like I would expect a fantasy world to actually be! 4th is a much better tactical game but I think it does not support the fantasy milieu as effectively.
I enjoy both tactical games and roleplaying so being in these two games works really well for me but I wonder how much the change in focus from 3rd to 4th edition changed the way other people play the game. Did lots of people start playing more hack and slash dungeoneering because the game shifted to focus more on that style?