Consider this, on the other hand:
Congressmen are individually elected and personally responsible for their earmarks. The earmark process gives the public a person who is individually accountable for public spending. Conversely, if earmarks were abolished (how would you abolish them?), then control over the details of spending (for example, deciding which district gets that massive order for Military Widget X) would be given to unelected bureaucrats. Then you would be like a European country, with all the corruption that entails.