Why don't vegans eat dairy products such as cow milk and eggs?

I'm just curious. I understand why they don't eat meat but why not dairy products? Milking the cows doesn't hurt them nor does taking their eggs. Now don't start ranting and getting all angry, I'm not dissing veganism or vegetarianism, I just want to know the motivations behind it. By the way I am aware vegans drink soy milk, I drink it too along with cow milk because they're both delicious--in my opinion.