The Zahn books are okay and I give Zahn a lot of credit for carrying the franchise through a moribund period. It's hard to believe today, but after Return of the Jedi the SW franchise was pretty much dead for almost a decade. Lucas was done with it, no one knew if there'd ever be another movie and little else was going on with it. Zahn's books changed all that and renewed interest in SW in a big way. I'm just not a huge fan of the stories, but I will acknowledge what he did for SW.
So did Lucas want to jump back in and do more films directly because of the Timothy zahn books ? I love the movies , but I've never really delved much into the background of the whole thing . What's the relationship between zahn and Lucas ?
Zahn was hired by Lucas to write the official follow-up after Return of the Jedi, and Lucasfilm had deemed them "canonical".
Whether or not Lucas was 'inspired' by Zahn to go back to the first 3 movies is unknown, but I doubt it, since they were 8 years or so apart.
When Disney bought the Star Wars franchise, they jettisoned all of the "official" continuity from the post-Jedi Lucasfilm efforts (several book series and several graphic novels -
Dark Empire was incredible) and completely rebooted everything, and that gave us The Force Awakens. It also deprived us of ever seeing Thrawn on the big screen as he was written in the Heir to the Empire series, where he was a serious bad-ass.