FUD goes both ways and the OpenDocument battle was particularly vicious on both sides.
However the code is literally a memcpy of a struct that is used internally. Not being designed for others to easily read isn't obfuscation. FWIW the XML formats designed for that purpose still fail horribly on that front.
Anyways I've worked on spreadsheets for 10 years. File compatibility is the hard part and the rest is easy by comparison (but still pretty hard).