Imagine 2 empty parcels of land in downtown Manhattan, one can have a giant skyscraper of any height built on it and the other has to be a single family home. The parcel of land with no restrictions is going to be worth exponentially more because you can built a massively profitable structure on it, the other one is so regulated that it isn't worth any where near as much. The more profit you could derive from a parcel of land the more its worth. Now I used an extreme example just to get my point across but the same principle holds on a small scale. If your house was rezoned for apartment buildings and the demand existed, someone would come in and buy it off your hands for a huge premium. Since in our hypothetical someone had just built an apartment building next to your house, the value of the land is already high, simply allow your parcel of land to allow more structures would cause it to rise in value.

On the infrastructure side, its a much better deal for you as well, the combined value of all the property taxes from the apartment buildings will be way more than if that lot had remained a house. Since the road, water, sewer and electric lines are already in place nothing new has to be built. You benefit from all those property taxes coming in from the apartment building while the liabilities to the government have barely increased. The local government can use this new surplus of taxes to build new amenities for you.

For traffic, sure but that's why you want to build more pedestrian friendly neighborhoods and public transit so people don't have to drive everywhere. Once you have enough people in a place you could open small shops so they can hang out around the building rather than drive everywhere.