You are missing a point though: this is the public administration side. They can (and should) demand any document sent to them to be formatted in a public open standard (such as ODF).
If anyone, it's the companies interfacing them that will have to bear those "interoperability" costs. At least until they also switch to LibreOffice or something compatible enough. IMHO this is much better than them requiring Office-formatted documents.
I agree that we should demand an open public standard but essentially it is still a cost nonetheless. We're just pushing around the costs to other companies instead of absorbing it within our own company. I think the government does stand a chance in demanding which standards they will accept though but for small companies looking to do business, it's gonna be a challenge trying to get customers, suppliers, partners etc to give you a format that you specify.
I totally agree with you, but this is a chicken-and-egg problem. Unless someone starts demanding such standards, the challenge will always be there.
Letting the administration be the pioneer in this front is sensible both morally and practically. Morally because the administration should be pushing for the greater good for all citizens, and practically because people/companies can not just "choose another provider and sidestep the issue".
Once nearly everyone is forced to have processes in place to interface with the administration using open standard formats, small companies looking to do business will have a much easier time asking for these formats too.
If anyone, it's the companies interfacing them that will have to bear those "interoperability" costs. At least until they also switch to LibreOffice or something compatible enough. IMHO this is much better than them requiring Office-formatted documents.