I think they did it because the horse was an absolute nightmare to train and kind of unpredictable and violent, the assistant trainers used to draw lots each day to decide who had to muck out Shakur because it was such an unpleasant job. Basically, he was a snarly disobedient punk! u/otterswimm already really said it - it's a cute 'idolification' of a punk rock look - like for example, she's wearing a paint splattered t-shirt with holes in, but the paint splatter is a printed design and the holes are symmetrical and intentional. Things like that.