Thats not the only reason, trust me, But I just thought Draco deserved it! I just think it is the best written, it it helped to transition all of the characters nicely.
Personally, I like Draco and hate Hermione. I'd of rathered Ron or Harry to punch him (Ron because he's had enough of Draco full stop or Harry to show he's not just a weak child to be bullied and that he's not afraid to stand up for himself) if it were necessary for Draco to be punched.
Hermione is easily the worst. Hell, even Voldemort is more likeable than her. Ron is overlooked, hence he's my favourite, along with Lavender. Hermione is overrated, the only reason I like her is because of Emma Watson.
I think people need to look beyond the horizon. Overrated doesn't equal 'best'. That's like saying Remus/Sirius (I can't choose between either) are only my favourites because other people like them (which is not true, might I add)
^ I like the last ones as well (from PoA, though), I can't stand PS/CoS, I get so bored (in CoS I just know what happens, but my sister says I know what happens in all the others, but there's just something about CoS that is so boring... sorry Tom-)