If I work with CSV files they are most often not comma-separated but semicolon-separated because of the numbers. An Excel installation localized for decimal comma would not read 'real' CSV files correct.
If csv-to-usv cannot cater for this type of CSV files, it would not be usable in a large part of the world.
Yeah they should add it. The tool is like 20 lines of Rust code. It's a thin wrapper around the csv Rust crate, which does support specifying alternative delimiters.
Have you maybe lost track of what post you're commenting under?
(I believe the answer is no BTW, the tool only supports , as delimiter in its input.)