So a few minor suggestions...
The Wooden material type looks really good, but overrides applied colors, making everything a shade of red.
The Standard Skin applies a slight color, which is good and all (prevents everyone from looking like monsters), but it prevents truly pale options (pure white, isn't even that light). To address this, I suggest an extremely pale opposite color; kinda like how some people wear green anti-reddening foundation. So a very light blue or teal, might be able to get more pale than pure white, without looking non-human.
Related to this, I also suggest other extremely pale colors. A faint pink for example, could closely approximate the skin tones of certain groups.
Drifting out of strictly colors for a moment: makeup options for freckles, visible veins, and bruises, would be nice.
Hair uses the main costume palette which seems fine. However, it can't do dark brown or black hair. It does true black video game no light reflected, but that is kinda weird. I suggest adding some extremely dark browns, such as the ones seen in the skin palette.
Similarly, some more vibrant reds for that dyed red hair look would be appreciated
Also, since hair overrides any texture applied (at least on the first two; no hair yet uses the others), perhaps remove the texture option from there (I know it's only the most tiny amount of storage, but still).
On the costume pallet, for names I would suggest glancing at what MS Office does. For example, "Blue-Grey, Darker 25%" "Magenta, Lighter 50%" (technically I think they might call that Red-Purple, but there the names need not be quite that bland). This would be both useful for colorblind people, as well as people wanting certain symmetry in the pallet they give their heroes (I admit when changing colors, I usually want the brightness to be comparable; that or stay within one color and adjust the brightness).
And finally, a quick painter or Apply-To-All option would be fantastic. Rather than starting from black and applying to each piece, we could quickly apply our basic colors and textures to all costume items to then refine as needed. If doing this, I would not put it on each piece (too easy to have an accident), but instead maybe from a third option of a painter's palette symbol within that top spandex menu on the right.