To each his own, but before thinking about resale value, anyone should think about its own pleasure. I didn't bought my Mustang thinking how much I will sell it back (hopefully I'll keep it for a very long time), I bought my Mustang with the options I wanted and made it to my liking, period.
Now I prefer mine to have some contrast, and played with the black paint and matte black to have some contrast, along with some red accents. I would not have it all black, but that's just me, everyone is different.
Just do what makes you happy!