There was already a pretty similar topic going on with loads of discussion. This discussion also briefly touched on general customization options.
In case you are not interested in going through all of this:
- Stuff like character customization of any kind does cost alot of devs ressources.
- Devs also want a coherent story, since the characters already have introduction cutscenes that would cause alot of work making them coherent.
- Stuff like this has generally no priority.