you are correct. While it is an abbreviation raw is not. It probably came from the old 8.3 file format and where letters in a file were always uppercase.
Yep, that's my excuse and I'm sticking to it. Plus RAW covers a wide range of file formats (although I think most are based on TIFF).
There is the other part that not all RAW files are necessarily raw data. Thus, I'm firmly in the RAW camp.