Not to mention Masako Nozawa is currently at the twilight of her career, so even if they figured out "Past and Present Protagonists" is a cool concept, it's just too late for that to even execute masterfully.

Especially getting respectable new roles in Dragon Ball is extremely difficult and very few find success there.

I would too if I was in their position, if you hand me the popular seiyuu list, if I look at the list for 10 seconds, I would thought "Man, I wish these popular youngsters are in Dragon Ball", but like I always said, due to DB overrelied on older cast while not doing the newer ones any favor.

To the point if they have the option to let new generation talents with dream to become part of their childhood and even a chance to become new face/representative of Dragon Ball or bury their dream to become one, they would choose the latter, 100%.