[int_19h]

Well, it is kinda weird to take what would otherwise be perfectly legitimate and meaningful syntax and make it a comment. E.g. Pascal uses (* *) instead, and there's no other construct in the language where those can legitimately appear in this order.

[tsimionescu]

Sure, but it's still a choice that C made, long before C++, so it's bizarre to see it in reference to how much worse C++ is.

As for the actual syntax itself, I do wonder why they didn't use ## or #{ }# or something similar, since # was only being used for the preprocessor, whereas / and * were much more common.

[int_19h]

/* */ is a PL/I thing that somehow ended up in B. I suspect that Ritchie just wanted multiline comments (which BCPL didn't have - it only had // line comments), and just grabbed the syntax from another language he was familiar with without much consideration.

Or maybe he just didn't care about having to use whitespace to disambiguate. The other piece of similarly ambiguous syntax in B is the compound assignment, which was =+ =- =* =/ rather than the more familiar C-style += etc. So a=+a and a= +a would have different meaning.