This is true, but IMO the biggest design improvement in 4E is greatly reducing the time to build bad guys. In 3.5, I would spend many hours creating a single bad guy (be it monsters with classes, NPCs, or whatever) only to have them get punked in the first 20 minutes. That really sucked as DM. I wasted a whole lot of time. Now, however, it's way simpler and I spend very little time working on bad guys. Who cares if they use all their powers or not? It's no longer a huge waste of my time and if the PCs prevail super easily, more power to them!
Yeah, I don't quite see it that way. As DM, I still take the time to design out an encounter room or rooms, still put unusual terrain in it, still put traps in it. I still do the work, my focus is just in many different other places.
When the PCs punk out the BBEG, it can still be frustrating.
In our campaign, we added a house rule that NPCs get an immediate free save (no modifiers) versus Stun, Sleep/Unconsciousness, and Petrification so that the conditions that totally remove actions have a chance to fail right away. This both helps to protect the encounter and incentivizes players to take Daze, Immobilize, etc. type conditions which although debilitating, do not take away all of the NPC's actions instead.
Personally, I cannot stand the Wizard Lock scenarios of 4E. It's extremely bad game design. Fortunately, none of our players have tried it yet.