I'm not rolling. A young Han Solo spinoff movie directed by the 21 Jump Street team is as out there for a Star Wars movie as it gets and they 86'd that once they saw how different that really was. Aint no way in hell Rian is out here in uncharted "I'm just having having fun out there" territory with the mainline sequel.
That's possible but it also could be that Kasdan was more 'hands-on' with this film and so wanted a stricter adherence to the script than he might have otherwise been. That along with Kennedy personally hating L&M might have been enough.