Voyager's ability to land on a planet's surface was used in a couple of episodes (The 37s, etc.). While I have no problem with the concept of doing so, I do wonder: what was the point of designing a starship with landing ability? They don't need to turn it completely off to do maintenance; in fact, they probably need to leave more of the ship active when on the surface than in space. (I doubt the Engineering section is heavy enough to counterbalance the massive overhang of the saucer section, so they'd need antigrav to keep from tipping over.)
Is there any good source stating (in- and/or out-of-universe) why Voyager can land? I'd also happy with good speculation, as I can't come up with any reasons other than it looks cool.