Also, encounter design in 4e is far more sophisticated and difficult than in previous editions
What, what, huh? You're surely not referring to 3e.
Based on timePreparing/timePlaying, 4e is twice as good as 3e. For a four-hour game session, I used to have to spend at least 8 hours in prep-time; now I can do it in 4. And it's not like I magically became a more-organized or more-efficient DM at precisely the moment 4e came out, so I'm pretty sure it's because the difficulty of creating encounters dropped.
Although this thread does bring up a good point; there's been "how to create a campaign," and "how to create an adventure," as well as "how to create NPCs," and "how to create monsters" articles written... but that crucial connecting piece, "how to design an encounter," hasn't really been explored in The Dungeon Master Experience or any other WotC product. The submission period is open for how much longer?