Nice point - but unless he's running a published scenario with very boring monsters exactly as written, I don't see how that can be so - even in the combat encounters.
Oh, I run interesting fights. I've got one coming up for tonight that is a combo action scene, puzzle, and violent tactical challenge. Running interesting fights has never been a problem for me.
What's become a problem is that there's less room in my mind for the fun, random stuff I like, and that I believe players having the ability to dictate the game is part of that. While I KNOW there are "players dictate the choices" powers in other games, in my experience, they'd always wait until I said "yeah, it works" before they'd move the pieces on the battle map or something.
Because even Wish had a counter. Finger of Death didn't work on everybody. Even if you cast your disintegrate spell, there were ways around it.
Nowadays, they can use a power that says "you slide the target three squares before attacking", and even if they're fighting Gandalf who is shouting "YOU SHALL NOT PASS!" they can easily slide him out of the way and get what they want.
And if I say "well, he said you shall not pass" they can point at their power card and say "but it says here he does" and come up with all sorts of creative reasons why that is. And if I say "no", I'm essentially breaking the rules of the game for personal story reasons, and nullifying a player's character choices. And if I allow it to happen, well then, really, what point does description and fluff play in the game, if it's all so bendable?
Now, I KNOW I can add on exception-based effects. I get that. But I don't want to have to add them all the time, and basically have boss fights be immune to crafty powers. I LIKE players being creative with their powers. But when our cleric plops down a power card, moves Orcus across the board because the power card says so, rolls a d20, declares he hit, and then rolls damage - all without even asking me to see if anything happens - then I get a mite tetchy.
I guess it might just be my experience, and others haven't encountered it, but it's definitely something I've seen. And it doesn't make me a bad GM, or anything like that.