I guess I have to be one of the few people to defend Chris Perkins here. He did nothing wrong at all. The rules say it can't target objects unless the DM says so. Chris is following the rules. I don't understand the pure disdain hurled at him for that.
Here's why I don't think it was a bad reason to give: The logical reason starts arguments.
Flash back to my 2e games:
Me: "There's a frozen door covered in ice."
Wizard: "I fireball it, that should melt all the ice off."
Me: "Fireball is extremely hot, but it only lasts for a fraction of a second, it isn't going to melt all the ice off."
Wizard: "What? It does enough damage to kill someone outright and you're saying it doesn't last long enough to melt a door?"
Me: "Yes, that's my ruling."
Wizard: "Well it's stupid. Look, a fireball probably has to burn at what, 1000 degrees Celsius? We could figure it out, but I'm guessing that melts ice in fractions of a second."
Me: "I don't want to start using physics equations to figure this out, let's just say it doesn't last long enough to melt the ice and move on with finding a different solution to the problem."
Wizard: "You aren't letting me be creative with my powers. This game is stupid."
Fast forward back to my 4e games:
Wizard: "I use a fire based power on the frozen door."
Me: "You can't, that power doesn't work on objects, only creatures."
Wizard: "Oh, yeah, you're right...that's what it says. Alright, let's get the Fighter to try to push the door open with a strength check."
This isn't to say that I wouldn't let some powers target the door. But if the point of the challenge is to use skills to solve it, I don't like people bypassing the challenge entirely by using powers.
Powers, to me, are the in combat method of solving problems with people attempting to kill you. Skills and Rituals are the out of combat ways of solving problems. And I like to keep the 2 separate if at all possible. Otherwise we run into the Wizard syndrome from earlier editions again. Why be good at a skill when there is certain to be a power that succeeds automatically when you have a chance of failure? My solution to this is simple. Powers rarely, if ever affect non-combat situations(utilities not withstanding).