There is a big difference between Cog and the C preprocessor -- the generated code actually lives within the file, and your IDE / type checker / linter will process it. Sure, they aren't hygienic, but for lightweight macros (which, in non lisps, is the majority of the macros people write imo) hygiene isn't a must-have.

I have found Cog to be very helpful while writing Rust code. I love Rust, but I'd prefer to write my macros in a different language (like Python). I also find debugging macro expansions to be much more painful than debugging Cog macros.