> I’ve never actually had anyone complain about me sending them ODT or ODS files since even the said MS Office doesn’t have a big issue with those.

On a Mac, I can read .doc(x), .xls(x) and .rtf without installing any additional software. I can’t do that with ODT/S.

90% of open data spreadsheet downloads could just as easily be provided in CSV format (looking at you, gov.uk).