To be clear, in general the vocative is a case eg in Czech and other balto slavic languages (except eg standard Russian while colloquial Russian is developing a new unrelated one).
In Latin tho, it’s more a relict. Other cases have relicts, too, still I wouldn’t say Latin has the locative.
I would argue that being a relict is a spectrum. Technically, it is a case with many syncretism to nominative, since it is obligatory for those nouns. In the context of LAtiN hAs sOo0 ManY cAsES, it’s not.
First, I wouldn’t count the vocative but let’s not get into this debate. Counting cases, Russian wins until you include other balto slavic languages or even Uralic ones.
Fancy is a very subjective term. Auxiliary verbs are fancy in their own way. From an orthographical viewpoint, French is quite fancy with all the silent letters, the way vocals are pronounced and stuff. French had like one spelling “reform” and it was like let’s make it more obvious we decent from Latin. Grammar wise it’s just like the other romance languages from what I know. They once got rid of the silent <s> and put a “gravestone” on the letter before (^) that has no other meaning than here was a silent s. Wouldn’t you call that fancy? Who would call it fancy? Mwa Moi!
How so? Except the first sentence which is obviously not serious, I would agree with all linguistic statements or at least not disagree with any.
I called it relicts but it’s basically what I said. Maybe vestiges is the better word in English, in German we say “Relikte”.