Words matter; spelling matters; grammar matters. These things give meaning to language. And while they may be alien to English speakers, diacritics and accents have evolved in the use of many languages with good reason. Because they too carry meaning.
Consider the popular Irish name Seán. It has become known around the world, and while some people write ‘Shaun’ or ‘Shawn’, most are familiar with ‘Sean’.
And if you’re speaking English only, then ‘Sean’ is fine.
Except in Irish, without the ‘á’, it’s pronounced ‘shan’ – and it has a different meaning.
sean (adj.) Old, aged; mature.
Add the ‘á’, and Sean becomes Seán, a proper noun, and a popular name.