Everything you explain points at no need to do client side hashing: what exact attack vector would be stopped by having it? (The only thing you bring up is reuse of passwords, but then you explain how that would be easily exploited if server was compromised, and it's even easier if client is)

I would imagine most developers unfamiliar with encryption would assume that client hashing is sufficient and not bother with server side hashing which is the only one that ensures privacy in case of compromise on the server side (nothing really stops client side compromise).