Earmarks promote corruption by allowing lawmakers to waste taxpayer money on projects that don’t serve the public good and instead serve their political or personal interests. They’ve gotten members of Congress in legal trouble in the past, so the ban on earmarks should be permanent.
Earmarks help facilitate deal-making in government, which helps lawmakers get legislation passed. They also help lawmakers from smaller or more rural districts bring needed money to their districts. As long as there is proper oversight earmarks help more than hurt.