Why is this even an issue? Microsoft has a (free as in beer) patch for older versions that lets them read and write the new .tlax files in addition to their native .tla files.

Unless I'm misunderstanding something, this is only a problem for people who a) are using software that is over 5 years old and b) haven't bothered to patch it in the meantime, so it's hard to feel a whole lot of sympathy.