The scene was a fun extra treat for the '77 rerelease, but it was not necessary for the story, and it does not make sense when taken in context of the larger story. As PCITSCH said, it doesn't make sense for Han to be talking with Jabba if he's trying to get out in a hurry. He says to Luke and Obi Wan, "We're a little rushed, so if you'll just strap yourselves in we'll get out of here." Why would Han say this if he just finished buying himself time with Jabba. Also, if Jabba is the most wealthy and powerful person on all of Tattoine, why is he hiking all the way out to Mos Eisley to shake down one of his former employees for money? Doesn't he have better things to do, like feeding Twi'lek strippers to his rancor while getting baked on spice? I thought that he had bounty hunters to take care of debt collection?

The scene is totally useless and should not be integrated into the actual film. Not on a permanent basis, at least. Like I said, it was fun to see it in theaters, but long-term it should stay as an extra on the side.