[TeMPOraL]

How about all non-hackers who don't know what a "file format" is, but may have important documents in decade-old formats? "Normal" people are not only not trained that they should keep upgrading lest they perish; they will ask you with bewilderment, "why I'm supposed to throw away that perfectly working machine after only 3 years?".

[aroch]

If they're not upgrading, they're not facing the horrible, insurmountable problem OP is.

[icebraining]

They are if they need to send a copy to someone with the newer version.