> So I personally just don't see the benefit from a less generalised version of coreutil tools
Others have pointed out specific examples, but the general reason (which I don't think I've seen explicitly articulated) is that CSV isn't strictly line oriented -- for intsance, records can span multiple "physical" lines, because line breaks within quoted strings are part of the field value, not separate records -- so line-oriented tools don't work with CSV generally (they may if you happen to have CSV where nothing inconsistent with a line-oriented view happens to be done, but that's luck not something that is generally true of CSV.)
I'm an experienced Unix admin, and I actually wrote my own versions of these csv tools long ago instead of using coreutils. I had a lot of different datasets to with with, and it turned it there were so many inconsistencies in the CSV data that I needed a tool that could handle it all.
It also became super simple to extract and munge data with options for tabular data. With two tiny commands I can exclude rows, include rows, sed columns, merge tables, and export new tables, all with just csv files. So it's pretty handy.
