Dude, the amount of money that politicians get in campaign contributions is tiny compared to the amount of money that is spent on lobbyists. The problem is that we have this class of people who are personable, who are well informed, have spent years creating relationships with other people in Washington, and who are very experienced at providing simple, one-sided explanations of the issues to congress-critters.

If campaign contributions were entirely banned I doubt it would make much difference, because legislators are too busy to pull information on every topic that they feel they need to Do Something about, and its the people with lobbyists who succeed in pushing out the (fraction of the) information needed.