The movie doesn’t need the Kessel Run to work, which means it should find brand new adventures and exploits for Han.
Showing Han and Chewie make the infamous run through space does nothing to enhance the mythology of the character, but it effectively takes away a significant source of his mystique.
The beauty of the character is that fans can project whatever they want onto him (the full-blown badass, the “shoot first” scoundrel or the self-aggrandizing, out-of-his-depth liar), but that goes away as soon as we receive a concrete answer to this long-running question.
By contrast, allowing Han Solo to make the Kessel Run (and providing a definitive answer to whether or not he did it) could be more akin to showing Boba Fett or Anakin Skywalker as children — two prequel trilogy decisions that have polarized Star Wars fans for years.