Directly, it isn't much. Indirectly, it could be much more. You can fire the rocket from a different location on Earth. Switching to a different orbital plane

Directly, it isn't much. Indirectly, it could be much more. You can fire the rocket from a different location on Earth. Switching to a different orbital plane is expensive. There are other benefits. Launch windows are usually limited due to the physical location of the launch pad. Launches are very often cancelled due to weather. There may also be something to be gained regarding ice hazards. Cryogenic rockets that sit along the Florida coast collect ice from the air. This doomed a Space Shuttle. Getting up to dry air before the launch could be a way to avoid the ice formation.