Why can't Star Destroyers land?

Even if ISDs had the ability to land on planets, I doubt we'd see it in the films. A ship of that size no doubt would need a very elaborate docking facility planetside in order to land safely. Planets like Hoth or Tattoine would be too primitive & remote to waste time, money & resources constructing such a facility.

 

It is not likely that the Empire would want to land such a huge vessel. It is most likely that Star Destroyers are not ment to enter the atmosphere of any planet. It would be easier to send out a platoon of troops than to try to land a craft of such magnatude.

 

"off-story wise, for the same reason in Star Trek they decided to invent transporters, because they couldnt show the ship landing and thus it became cannon that it canot land, in-story wise"

Like it did in the first movie?

 

actually, we never really see the Venators landing in-combat, they seem to be mostly flying docking bays by the time ROTS comes along, but the Acclamator class, was basically a flying troop transport,
but by the time ANH takes place, there's no point in a massive troop carrier.. the Empire doesn't have to invade much of anything, they're already there, I'm sure there are very few planets within the empire that don't have their very own garrison of stormtroopers..

..besides a "landing barge" carried by a standard SD, is large enough to carry an ATST, at the very least, that means the barges themselves would be about the size of an AOTC stardestroyer,
and assuming a regular SD has room to carry several of these, you begin to see how infesibly large an SD is, and why they'd be a pain in the a$$ to land

 

The part about the Empire not needing a troop transport is probably the most plausable answer.

The Venators are parked on Coruscant, and one can be seen landed on Kashyyyk. It's strange though that the docking bay even on the SSD doesn't seem to be able to launch anything larger then a shuttle or TIEs (ESB), maybe they have other openings that we don't see used. I doubt the barges are as big as the 752 meter Galactic Transport.