4e powers seem similar at first glance, partially because they've all got a similar power level compared to other classes. However, what look like subtle differences in the powers behave very differently in play, and this opens up a lot of synergies ripe for player cooperation (this is why 4e has the best tactical combat of any edition). So the dragonborn can use dragon breath on an area, but in preparation for that the Fighter can drag an enemy into the blast radius, the Warlord can slide the Fighter back out of the blast radius, and the Ranger can hit the boss with an arrow in the knee both to do massive damage and to make sure he can't get out of the way quickly enough.
Now sure, you can cooperate like that in any edition. But 4e makes it both easy and effective. I'm not exaggerating when I say the party will pull of a trick like the above in almost every fight of the campaign (though that was a slightly elaborate example), and sometimes multiple times per fight. (Pro Tip: lining up minions so someone can push one into another, causing them to knock each other out (or shatter in the case of skeletons), may eventually stop being hilarious, but my group never reached that point. It's bowling for minions!)