It depends what you mean by 'matters.' It's linguistically interesting (and, to linguistic conservatives like me, rather irritating), that's all I'm saying.
Don't understand your point about testicles, lacb. According to my dictionary, 'testicles' is the standard (polite) word in English, first attested in 1425. The first recorded use of 'testes' (plural) is in a technical dictionary of 1704, where the word is defined as 'the Testicles of a Male.'