Definitely this - they’re some of the best military science-fiction and, along with The Clone Wars series, give Order 66 a lot of added weight.
I feel like it will be bad because authors won’t have freedom to make things their way.
The series both disproves and proves this statement - Karen Traviss definitely had the freedom to make things her own way until she didn’t. She stopped writing because she didn’t feel she could make it work with the new status quo (although I think if you squint a bit and lean into the “legends” idea, that these are legends which may have happened from a certain point of view even if all the details may not be correct, it can still work, at least for me).