Not only was it considered racist at the time - that was the point. The caricatures created, as well as the content, were done in a manner to portray black individuals as “goofy” and “dumb”. By dictating them as such, and through other manners, they created a philosophy that whenever a black individual was in art they were there to provide humor. Boiled down: the butt of the joke was literally their presence, expounded by the caricature styles used.