Because realistically, this is the *only* way they can make it work.
There is another way. The Walking Dead: Firefly edition. . . Stop throwing things at me.
His absence would obviously not be addressed in this very early announcement.
Between the show ending and the movie, both Sheppard and Inara left the ship. It was stated that the crew occasionally used his planet as sanctuary. So leaving him out of the stories would be fine for the timeline.
The show was 20 years ago. They want the new series to be set between the original show and the movie. To use the same actors, it would be easier for the show to be animated than try to make the actors 20 years younger. The alternative would be new actors to play the same characters which would not be favorably received.
Also voice acting would require less time of the actors, and they do not all have to record their lines at the same time. Nathan Fillion, Alan Tudyk, Gina Torres, and Morena Baccarin might have other acting roles right now.
(I know, I'm an idiot for that... after I put my computers back together, I'll go hide in the corner).
Is that some sort of flex? You put a computer together? Egads . . . no one else on this site has probably every put a computer together.
congrats, you made me feel like 0% less intelligent than I was before
Hey whatever you want to do with your time . .
Make it myself? But I'm a physical organic chemist!