Well, its really because the skin situation is quite fluid with Box, as initially they all started out as 2k, but newer planes have been released as 4k, and some existing ones have been upgraded to 4k.
This in turn means that the normal maps have been changed as well to fit 4k for these newer/upgraded planes, and don't necessarily fit well as well with the old 2k skins.
A lot of the skins these days are 4k skins anyway, all from Bodenplatte for example, sooner or later everything is planned to be upgraded to 4k templates anyway.
What it would mean would be, that I on my end wouldn't see your skin if it an old 2k skin, but would if it was a newer 4k skin (which is increasingly the more common), and if you were wearing a 2k skin, my mod if used in conjunction, would re dress you in a 4k skin on my end, which will also dress all the ai in 4k correct marking skins too.