Different field, but it drives me crazy that people talk about Chinese philosophy and insist on using Mandarin pinyin for it. Mandarin is language that evolved from Classical Chinese thousands of years later! There are other, equally valid contemporary derived pronunciations like Cantonese or even Japanese and Korean. The reason to use Mandarin is because it is the most widely spoken language derived from Classical Chinese, but it's 100% not how Confucius or any of them spoke!
It's just the standard. So it self ratifies. It is quite possibly one of the worst options though given how many important language features are lost in it.
Cantonese used to be the preferred, and probably is to some, but even that is far from ideal and was chosen because while it preserves more important distinctions, it also happens to be/have been a very prominent Chinese language, with a moderate level of standardisation. It wasn't chosen purely on its linguistuc merits over others.
I can't remember who it was but there's someone out there who uses a fusion of Cantonese and Hokkien, where they pronounce the initial from one and then the coda from the other or something, though I can't remember which way around they did it.
Really depends on your priorities I guess.
What else would they use?
Of course they could pronounce the words in any modern Chinese language, but why not pick the largest and most standardized one?
That's like complaining at names like Jesus, Paul, Moses, or Peter (with their English pronunciation) because that's not how those biblical figures pronounced their own names.
What terminology should we be using? Old Chinese reconstructions on Wiktionary always look so wildly divergent to me.