It probably seems extra complexity for you, if your language does not use it. For native speakers it is just natural and not using it would be at least weird.

We could ask the same question about articles . Those ‘the’ and ‘a’, why use them? It only makes English language harder to use! ‘Apple is apple’ why add another meaningless word?

Of course after learning and using English for years I see the meaning of ‘a’ and ‘the’ and thy feel quite natural for me to (though sometimes they still make little sense to me – all the fights whether ‘The’ can be used with some proper name or not). The point is: a lot of features of a foreign language will fill alien and unnecessary.

Maybe more on topic, that is how/why gendered words work in Polish: noun gender is usually linked to how it ends (but do not confuse that with suffixes of grammatical cases). Virtually all Polish women names end with ‘a’, so any other noun ending in ‘a’ sounds feminine and would be used in similar way. And sometimes it just ‘rhymes’ – like in ‘to jabkło’ (‘this apple’ – neuter), ‘ta gruszka’ (‘this pear’ – feminine), ‘ten banan’ (‘this banana’ – masculine). Of course thing get much more complicated than that (like in every language, just in different parts of the language).

People were just talking in the way that it was convenient for them. And thousands years later scholars called this feature of particular set of languages ‘gender’ because words used seem to be related to genders.