"Better" depends on what you care about. _konniti-wa_ (which is the Kunrei-siki romanization of こんにちは, _konniti-ha_ is Nihon-shiki form that preserves the irregular use of は as topic-marking /wa/) and _susi-o_ (again, Kunrei-siki ignores a native script orthographic irregularity and romanizes を as _o_ not _wo_ ) are more consistent with the native phonological system of Japanese. In Japanese coronal consonants like /t/ and /s/ are regularly palatalized to /tS/ and /S/ before the vowel /i/, and there's no reason to treat _chi_ and _ti_ as meaningfully different sequences of sounds. Linguists writing about Japanese phonology use it instead of Hepburn for good reason.

Obviously, being more transparent to English-readers is also a reasonable goal a romanization system might have, and if that's your goal the Hepburn is a better system. I don't have a strong opinion about which system the Japanese government should treat as official, and realistically neither one is going to go away. But it's simply not the case that Hepburn is a better romanization scheme for every purpose.

Should we also change other languages’ orthographies to make them easier to pronounce for English speakers? “Bonzhoor” instead of “Bonjour”?

You are very, very likely to find people who prefer "sushi wo tabemasu", because standards are great.