I am confident it has been asked for many times, but if we do not ask we do not get. There are just so many slots before people will have to delete characters, and they will eventually fill up unless we start deleting characters passed over each season into eternal.
It is so much more logical to simply facilitate a REBIRTH function for existing Eternal classes.
At least consider it please BLIZZARD.
Thanks for listening. 
you are right, it has been asked quite a few times.
I certainly see it as a QoL thing they could add.
In theory you can “manually” rebirth your characters anyway, since names arent locked etc. But yea, a dedicated rebirth option for sure would save some clicks and eventually has a better feel to it for eternal players.
I have deleted 40 max level characters at this point because I play all classes every season. 
How about hardcore get their own dedicated slots and softcore the same? Since you cant share between the 2, this would free up slots for people that play both.
I used to do one build per season. Did 4 last season, 6 this time, all from a different class. Obviously had to delete characters.
Gave the same name to new ones, choose the same face (there are only 3 or 4 options), same hair, even same outfit. The rebirth can be done manually without too much effort but obviously being able to do it with a single button hit would be better.
I am no dev but I believe adding the feature should not require too much work. Of course, every change, even if minimal, requires testing but I am confident that the feature will be added at some point.
Yes, please! The rebirth system needs to come back. Deleting characters and recreating them feels wrong. I wanna rebirth my chars for the new season and only create new chars when I feel like it.
All four people in my regular group, including myself, would love to have some kind of Rebirth mechanic.
I am not quite as voracious with classes as you, but that’s a good point as many people do play several classes in a single season.
EDIT
Adding more character creation slots is not a solution. Many people do not want to scroll through 100 characters, so the cap they have is fine, a rebirth is still to me, a sensible and more logical solution.
Be really fun to get a 5 season rebirth streak or something like that on hc/sc.
Whooooooo frackkkinggggg carrrrrrrrrrrrrrrres?
It could be a permanent feature rather than by limited seasons, if I read that correctly?
I do when the same class has two different builds, easier for armory swapping. Can put different runes etc in per build requirement because the armory hasn’t got rune and gem memory - yet.
Huh? 
That’s not how ‘rebirth’ works.
Imagine its year 2025 and there are still games out there where you cant buy additional character slots in the precious ingame shoppe. Canst thou believe this people? 