I believe D&D4 teaches players bad lessons.
Playing with a group who are veteran D&D players across 5 editions of the game and 4 decades, because of D&D's focus on tactical encounter-oriented gameplay, when monsters from one encounter would, at my command, scurry off to the next room to alert their allies, the players rebelled.
I was breaking the notion of Encounters! I was taking two or three Encounters and turning them into one big encounter! What about our Encounter Powers, what about Milestones?!
Now the issue here is that the monsters were behaving in exactly the same way they'd behaved under every GM at the table for 30 years, and in exactly the same way all the players were used to. What had changed?
The system. That was the only variable. The one player who was new to the group and hadn't played as much D&D started using the phrase "the monsters want to win" as his way of expressing this--to him--radical notion.