more or less I was referring to the ability to add 3rd-party custom skins.
as for the VST example, let's say that price wasn't an issue, all three are available for the same price (freeware, donationware, we're-going-to-buy-you-out-of-house-and-home-ware, whatever you want to imagine the price to be).
If there's no difference in price or functionality, eventually the visual aesthetics come into play, be it for purchasing hardware or software.
Sure, if you don't want to use skins, that's fine. You don't have to use them. However, some people (myself included) would like an added ease of customizability when it comes to the visual appearance of Mixcraft 6 (and/or 5) as it currently stands. It's a real pain in the butt to have to back up the entire mixres folder anytime I want to modify the current MX6 skin.
I feel like I should also note that mixcraft 6 is practically ready for multiple skins as it stands - check out the "mixskin.ini" file in the mixcraft program folder. You'll notice within the first few lines (second line, actually) the .ini file mentions the ability to "use another skin". My only guess as to why this is here is that the acoustica mixcraft team was being future-ready, in case someone is compiling a new mixcraft skin .ini file but they don't have all of the necessary images for said new skin, they can call upon an image found within another skin. Point being, it's practically there, all they have to do is put it in the settings menu.