Final guess here:
When they implemented the Hi-Res font, they made it with transparency stroke, and it looked nice for character names.
But since the game uses that font almost everywhere, this change also made some text other than character names a bit difficult to read.

Maybe it is not easy to make the names transparent only and leave other text solid, so they decided to make them all solid to prevent the problem text become difficult to read...
So it seems not an accident.