I was wondering, why FDev haven't implemented save slots yet.
One reason could be: They want the Holo-Me to be our lasting in-game avatar that doesn't change radically every other minute! Hence it could be a design decision rather than an omission.
They could have achieved this by freezing the avatar after the initial creation and never let us go back to it (like in other games). But this wouldn't have allowed later refinements. With the current implementation, we can tweak our avatar a little bit on long super cruises to Hutton Orbital - including changing our space suits and facial paintings (of which some can be purchased and hence create needed revenues).
If this is true, however, I feel that the Holo-Me button is a little bit too present in the UI.