Here's why George Lucas added Jabba the Hutt and Boba Fett to the original Star Wars movie. To commemorate A New Hope's 20th anniversary, Lucas released the special editions of the Star Wars trilogy in 1997. While this gave viewers the opportunity to see the three movies on the big screen once again, it wasn't without controversy. Longtime fans took issue with a number of changes Lucas made to the films, with Han Solo's confrontation with Greedo being perhaps the most infamous example.
To be fair, some of the Star Wars special edition alterations are positive, but audiences felt others were largely unnecessary and made the films worse. One example of such a change is the reinsertion of the Jabba the Hutt scene in A New Hope, where Han Solo has a short talk with the gangster before flying off to Alderaan. In addition to having arguably distracting CGI, the sequence also disrupts A New Hope's pacing and comes off as redundant (much of the information relayed was in the earlier Greedo scene). Another sticking point for critics is Boba Fett's cameo, which features a fourth-wall breaking mug at the camera. It's a sequence many would cut, raising the question as to why Lucas felt the need to put it in the special edition. There are a couple reasons why.
It was always the plan for A New Hope to have the Jabba scene. During production, Lucas shot it with actor Declan Mulholland standing in for Jabba. The idea was Mulholland would be replaced by a creature added in post. However, technology was very limited at the time and Lucas also didn't have the money required to finish the scene as he wanted. Neither of those things were an issue when Lucas revisited the film for the special edition, and he was able to create a digital Jabba the Hutt so the scene could finally be part of A New Hope. This is in line with Lucas' claim that the special editions allowed him to realize his full vision for what the Star Wars trilogy could be. The technology finally caught up with his ideas.
As for Boba Fett, no formal explanation has been given for why the bounty hunter was added to A New Hope. Odds are, Lucas (who knew of the character's immense popularity) thought fans would appreciate another Boba Fett appearance. Ironically, Boba's cameo was largely criticized for being pointless fan service that didn't add any substance to the scene. In contrast from Boba's original movie introduction in The Empire Strikes Back (the infamous "No disintegrations" scene), his role in A New Hope came off as a bit of a joke, as he pauses to look at the camera and call attention to his presence.
It's understandable why Lucas felt the need to put the Jabba scene back in A New Hope. This was something he always wanted for the movie, so he didn't hesitate when the opportunity arose. "Kill your darlings" is an old industry phrase referencing the need to leave certain scenes on the cutting room floor, but creators can find it difficult to part ways with sequences they've grown attached to. Lucas obviously had a fondness for A New Hope's Jabba scene, and he certainly had the right to put it in the special edition. Even if A New Hope is arguably better without it, Lucas couldn't resist the chance to finish something he hoped to do back in the 1970s.