The rationality of land battles in interstellar conflicts?

When you have a fleet of spaceships capable of glassing a planet having to bother with conventual conquest is kinda unnecessary as they have to be suicidal or zealotic to not surrender when entire cities and continents can be wiped out the only reason to have boots on the ground would be when an enemy interception fleet is trying to stop the siege, then seizing important cities and regions of interest becomes the pragmatic choice to capitulate the planet alongside you can destroy anything of use to the enemy when you have to retreat from the system.