When you have a game that appears to require you to choose the pixel you want to land on from space, then lands the ship randomly in it without permitting manual atmospheric flight or choosing a specific site you want to land at, having a way to move to somewhere else (the next pixel, for instance), a way to move to somewhere that lacked the space for the ship to land on (which could be some distance away), a way to allow travel through environmental conditions which the space suit doesn't protect against, a way to transport cargo into\out of the ship to a storage area, etc. a ground vehicle could be quite useful\neccesary.
The only reason that they would have decided that ground vehicles "aren't really necessary" would be if the game was designed so that there was no reason (whether looking for resources, "Points of Interest", quest items, etc.) to move more than a small distance from wherever the ship is landed by the game, regardless of where a player selects as a landing spot from orbit.