We're off on a tangent here, but basically, Lucas had three good options:
1) keep Han frozen, and make Luke, Leia and Lando the new trio, and maybe end the movie on the promise they'll recover him next,
2) do the Han rescue, but start it in medias res and get it done in 5-10 action-packed minutes, much like a James Bond opening sequence, or
3) contrive some reason why they need to infiltrate Jabba's Palace anyway. Random brainstorm example: maybe there's some space pirate willing to join the Rebel attack on the Death Star, but the pirate chief's daughter was just captured by Jabba, and he won't devote his forces until she's rescued. So, if our heroes have to raid the Palace for the greater good, they can get Han back while they're at it. This could also perhaps lead to some fun and games where the pirate's daughter gets the hots for Han, and now Leia's on the tough side of a romantic triangle. May Han likes this new woman's devil-may-care spirit, but finds she's only against the Empire for revenge for their part in her capture, and ultimately only interested in herself. She would have been perfect for the Old Han, but the New Han believes in being a part of something greater, and therefore chooses Leia. Like I said, random brainstorm example.
In any case, spending 25% of the movie* on Han's rescue, without any other plot benefit, was not a great move.
* I just checked. The whole action on Tatooine takes up pretty much exactly 25% of the movie, not counting the end credits.