Concrete is more expensive than asphalt, but it lasts longer and is easier to patch. The bumps you guys are feeling is from contractors not knowing what the hell they're doing when they put it down. The only other reason for concrete not being smooth is that the subgrade has deteriorated. That situation can be corrected by injecting urethane under the concrete to raise the low spots.
I drive a concrete truck for a living, and it amazes me the people that pour concrete (and have for years) and don't have a clue what they are doing. Not just Joe Homeowner I bring concrete to on a saturday morning, but contractors that make their living off this stuff. It ain't rocket science......