If you're allergic to Japanese honorifics, being on a last-name basis would be enough without the stifling formality of constantly using Mr./Ms. Unlike Japan and its 100 layers of social formality, the US wants to be on a first-name basis, instant besties with everyone they meet. You're simply not going to translate that well, so you might as well keep the honorifics to add a certain amount of foreignness in.
If you're allergic to Japanese honorifics, being on a last-name basis would be enough without the stifling formality of constantly using Mr./Ms. Unlike Japan and its 100 layers of social formality, the US wants to be on a first-name basis, instant besties with everyone they meet. You're simply not going to translate that well, so you might as well keep the honorifics to add a certain amount of foreignness in.