Kitsune said:
Well, clearly because the wizard is a wizard, and that's what wizards do.
I think this is where your argument breaks down. What wizards do very much depends on your view of fantasy. I'll use the LOTR movies as an example (I would use the books, but its been a very very long time since I read any of them).
Gandalf is a powerful wizard, but he doesn't do a lot of raw damage. Often times he's just beating orcs down with his staff.
Further think of Conan vs those evil mages. They are powerful, but Conan still takes them down.
But even if we assume your argument is right, wizard should do what wizards do right? So what can they do in 4e.
I now point you to the pregen wizard from DDX, who has a largely overlooked ability:
MAGE HAND AT WILL!!!
If you read the power its actually quite powerful. Think of the roleplaying potential of being able to do lesser telekinesis whenever you want...at first level even!! In 3e, you throw a magic missile, maybe a color spray, and your spent. Now I can play a wizard that sits in a chair while my magic turns the pages for me. I can have a servant who I give a telekinetic smack if he messes up. My guests are served by floating dishes that arrive to the table.
So yes, while the basic mechanics of each class is the same (as far as how powers work), the powers have a huge impact on how your roleplay them.