In or out of universe, it would be awkward and weird to step on the pad facing the back of the room, and then look over your shoulder to ask the operator to please energize.
Beaming up facing away is likewise awkward, and could also be momentarily alarming if you're unfamiliar with starfleet shipsbeing beamed: you would at first glance appear to be in a very confined space.
Instead, starfleet would want visitors' first view of the ship to be a nice open room with a (hopefully) pleasant face to greet you. Presumably, the system can rotate you to face the right away. When Lwaxana was beamed up facing backwards, the system may have been confused by the fact that she chose to kneel for that one.