NO, he introduced a complication of the concept
Consider this: how would you recommend yaya to do with 10x20 ASCII fonts? For the 10-dot row of a char, you must use a byte and half a nibble.
And yaya decided to use hexa digits in the font file. I would rather believe that the decision was an effort to conform to the original concept.
As said this is perfectly OK, it is not a problem at all as long as a "same extension" is NOT used.
It might be also OK and also "not a problem" even if the same extension is used, considering the world is diversified, not monophyletic. There is no absoluteness in anything. Compare with this:
MS uses EXE for DOS executable. But in Windows, it still use the same extension.
It is just not wrong doing such a thing.