Think about it folks:

Here is Luke, now a jedi knight badass. He doesn't need a effing noisy-ass bike. In fact, he'd likely use his force powers to conceal his arrival until he gets right to the gate.

I mean, where is he supposed to park? In the dunes? On the path? At the door? Why? Why not just have him keep going and fly up through one of the windows like Harry Potter on a broomstick?

Better yet, why the hell didn't Ben have that bike in ANH when the sandpeople were out attacking Luke and stealing crap with his speeder? he was walking around with...wait for it...a hooded robe like some, oh I don't know, entrance into the film as a mysterious figure.

Add Ben on a speeder and have him give that dragon call and then have him swoop in do a CG backflip off the bike, and then whip out his saber and start taking out Tuskens.