Quite apart from the fact that Enterprise was going at warp, I could not fathom how Scotty in the movie could scan the ship at such a great distance with enough accuracy to transport safely (still, in for a penny).
Well, that was supposedly the reason they locked onto the engineering deck, because it was the roomiest part of the ship and thus the safest to beam into. That's explained in the novelization, though it was cut out of the final film (if it was ever actually in the script at all). And as you'll recall, it wasn't
quite a safe transport, because Scotty materialized inside a coolant pipe. He was lucky he beamed into liquid, something that could be pushed out of the way by the ACB, instead of a solid bulkhead. (So in that sense, the film did demonstrate that it was a hazardous undertaking, not something you'd want to do routinely. I should've given the screenwriters more credit.)