The expansion costs nearly as much as both Witcher 3 expansions, and CD Projekt Red explains why
Tl;dr; expansion pretty much change whole game, reworks core game mechanics and adds whole new district. Plus Idris Elba and more of Keanu with expansion having almost as much lines as core game.
I feel like everyone should get access to the game rework, not just the people who buy the DLC. This what the base game should have been, what they promised.
And they do - the expansion is the expanded content. The rework is a patch that launches at the same time that goes out to everyone with and without the expansion. This is similar to how CDPR did The Witcher 3 expansions.