Cause Disney for some reason has re-imagined Luke as a colossal failure.
Luke never followed Jedi dogma, to the contrary, he denied them and followed his own path. Rushed to save his fiends, refused to give up on his father.
In doing so, keeping his personal attachment to his friends, his sister, and his father those he loved, he saved the galaxy, and brought about the return of the Jedi his way.
That is Luke.
Disney does not see or know the character. This is a different character.
And if he does not allow Grogu to choose both, it betrays everything Luke learned, experienced, and was.