Although I have no idea on how scripts can improve skins' functions, the security issue that MenthiX mentioned is not a big deal I think.
If it is done, then while importing such skin packs which include scripts, a warning sentence about this can be displayed in the Import window as if a script is being imported. Plus! doesn't get very bad reputation from its scripts, so why would skins with scripts be a problem for it? Moreover, combining two biggest features of Plus! to make things more excellent would be very good imho. Go vikke