KarinsDad - again, I think you're applying a double standard.
If doing X is clever, it's always clever, whether or not the rules support it.
This argument is illogical.
When you were 3 years old, adding 2 plus 2 was clever.
Is that still clever for you?
Clever is relative based on the scenario and options available at the time. Clever is doing something that you rarely do and something that is exceptional, not doing something that you do all of the time (like your players repeatedly using forced movement to push a foe into a hazard).
It's not that people think less outside the box, it's that the box has gotten a hell of a lot bigger.
Given the proper tools and a wider selection of them, people can be a lot more effective. That doesn't mean that they use those options in a clever way. In fact, the opposite occurs. Necessity is the mother of all invention. When the necessity is no longer there, the invention, inspiration, and ingenuity peters out. When all you have is a hammer, every problem is a nail. When you have an entire toolkit, you no longer have to use the hammer in innovative ways.
I've come to the conclusion based on your examples that you appear to be confusing clever with awesome. In one of the first 4E encounters that I ever played in, I managed to save a fellow PC by using Thunderwave to push 3 foes towards a pit. These 3 foes were previously stomping the crap out of my fellow player's PC and he was in single digit hit points quickly and about to drop. It was an awesome event because my Wizard hit all 3 monsters, knocked 2 into the pit, and knocked the 3rd monster prone. But mostly it was awesome because I saved the PC of someone else at the table. There was a lot of cheering. It was a cool moment in the game and some players still remember it 3 years later.
But, it wasn't especially clever. The entire purpose of Thunderwave is to push foes either merely away, or into disadvantageous positions. There wasn't a damn thing clever about it at all.
Just probably like your players, my forced movement was awesome at the time to the people playing. Players laughed and cheered over it. But also like your players, the concept of pushing foes into a hazard wasn't clever. Not even a little bit. Even playing the game for practically the first time, it was 4E 101 and obvious.