ICANN (as well as other supporters of the transition) believe that even the appearance that the US has control over ICANN is damaging to their ideal of keeping

ICANN (as well as other supporters of the transition) believe that even the appearance that the US has control over ICANN is damaging to their ideal of keeping the Internet global, rather than devolving into numerous regional, government-run internets. ICANN doesn't want the Internet sharded under the pretext, "The US controls the Internet, so we'll create our own." Whether this transition will help prevent that from happening remains to seen.