She's one of those ones, like a Tarkin, Fleet Trooper, Wedge, etc., that I think people anlmost universally would like to see on a vintage card simply because it never happened in the original line but "should have" to many.
There are this handful of figures that people inevitably customized when I was young and the modern line didn't exist... Slave Leia was the advanced effort, but she was one a lot of people tried. Fleet Trooper, Capt. Antilles, Wedge, Dak, Different colored astromechs, Stormie Han, Imperial Scanner technicians, Black DS Troopers, Grey Imperial Officers, Tarkin (using the one Black Hole figure's head was quite popular on this), Rem. Helmet Vader, Hoth Rebels in white, Hangar Tech Rebels, and a variety of Cantina guys like Bom Vimdin, Dr. E., Wuher, Yerka Mig, Tonnika's, etc.
There was just this list of figures that people would often try before the modern line came out... The more complex the less tried them, but figures like rem. helmet Vader were where I learned how to use my dremel to hollow parts out, haha. Lots of Slave Leia's tried... Not so many looked great, but some were really impressive by those who could sculpt.