It could be due to the context in which the piece was composed and how it was presented as a means to introducing jazz to a predominately European and classical listening base in NYC during the 20s. The “cultural appropriation” criticism is actually valid to some degree due to the fact that Paul Whiteman purposefully programmed it beside other New Orleans style jazz tunes (such as those from the Original Dixieland Jass Band), perhaps as a means to compare the quality of each style, and suggesting that jazz was “better” if merged with a more sophisticated form of music.
It's not a valid criticism. Jazz utilizes instruments and a system of harmony developed by Europeans. The guitar, trumpet, clarinet, piano, and so on aren't African, Asian, or Native American instruments; they're European. The chromatic scale and diatonic scale which are fundementally the bases of all Western music, is what Jazz developed from. It's also understated just how much of an influence American folk music and native american music had an impact in the early development of ragtime and later jazz, it wasn't just African music passed down through generations of African Americans. Without European Classical Music and Western music in general, jazz in its entirety quite simply would not exist. Without African Americans "culturally appropriating" European music, jazz would have never come to fruition. So to turn around and criticize early (white) 20th century composers influenced by jazz as "culturally appropriating" African American culture just comes as daft, ignorant, and frankly annoying.