They re-did the adaption of Star Wars but kept the original adaptions of ESB and ROTJ. It's a little odd but makes sense. To replace Al Williamson's work would be criminal. From what I can recall they wanted to have Al redo the adaption all himself because he didn't have anything to do with the original and they wanted an artistic continuity between all three. But Al declined because he didn't think he'd be able to do as good a job as he'd like. Despite this they went ahead with a new adaption anyway and were successful in convincing Al to do inking.

While I can appreciate the sentiment I think they should have left well enough alone since they couldn't convince Al to do the penciling. The artist who replaced him's work is very loose and doesn't jive at all with Al's adaptions. It also places a very heavy emphasis on featuring the special edition's changes over focusing on what's happening in the story. Howard Chaykin's adaption may not be on the same level as Al's but at least it had character.