It was specificly told that they will not use sliders ...
But threre still are ways to create customization a bit more comples, even without that thing.
For example ears, few faces for Elfs, or Tieflings could be quite nice, but those ears are looking horrible.

(yes, i am a perfectionist in this)
Or facial scars, again for some unknown reason tied only to specific faces.
Or complexion, is that so dificiult to add option to choose freckles? Dunno, Fallout 4 did that 6 years ago. :-/
I can work with choosing whole face, but right now we are choosing whole head like in Kotor (18 years ago) and that is not so impresive for AAA title in 2021, even if some of them looks awesome. :-/
I'm unsure how much work it would be for them. They've said in interviews that they're using some kind of face scan method of real people's faces and that they're very proud of the result. Adding sliders is probably possible but it might not be in their wishes to do so.
Yup ... they said that they scan over 40 people, creating over 150 different heads ...
Then i wonder why do we have acess to only 6(?) per race. :-/