https://screenrant.com/frasier-reboot-niles-return-david-hyde-pierce-response/

David Hyde Pierce comments on whether or not the upcoming Frasier reboot on Paramount+ can work without featuring the younger Crane brother, Niles.

doesn't he want to be a part of it?

Frasier revival originally had Frasier and Niles Crane opening a black-box theater together (https://www.yahoo.com/entertainment/frasier-reboot-originally-had-kelsey-200000331.html)

The idea for Frasier and Niles (https://screenrant.com/frasier-reboot-niles-original-plan-theater-unseen/#:~:text=The%20idea%20for%20Frasier%20and,but%20ultimately%20decided%20against%20it.) to run a black-box theater (https://www.avclub.com/we-could-ve-seen-frasier-and-niles-running-a-theater-1850932455) was considered, but it was challenging to proceed without Niles (https://www.vulture.com/article/frasier-reboot-showrunners-interview-kelsey-grammer-niles-writing.html). The creators discussed the possibility of making Niles the new Maris, but ultimately decided against it.

Frasier Fans Are Wrong: The Revival Is Better Without Niles (https://www.looper.com/1446410/frasier-fans-dead-wrong-revival-better-without-niles/)

Frasier fans keep bemoaning the absence of Niles, but the stark truth fans need to realize is that the revival is a far better show because of his absence.

Frasier's Original Finale Explained Why David Hyde Pierce Won't Return As Niles In The Reboot (https://screenrant.com/frasier-reboot-original-ending-david-hyde-pierce-niles/)

David Hyde Pierce refused to return in the Frasier reboot and the reason why has long been explained in the original Seattle-based finale.