Your argument kinda sounds right when you just imagine it... but doesn't hold weight once you actually experience them.
If this text isn't done like this then you have to either omit it entirely, possibly leaving out relevant details, or just put them next to the normal subtitles. The latter doesn't work at all for me, because I can't distinguish which text relates to what quick enough.
For instance translating the text on a piece of paper by writing the translation above the piece of paper.
How it is written in this case, in charcoal, on the paper, in perspective, seamlessly blending into the paper, makes it seem as if, for whatever reason, the same text was written twice on the paper in English and Japanese.
It's even more unnerving when the text be written and the English pencil charcoal appears out of thin air next to the Japanese charcoal that emerges from a pencil.
It suggests that the character itself is writing the English text, or that it magically appears.
If it were simple subtitles, it would be clear that these were translations, and that in the actual story there is only Japanese text.
Notwithstanding the impressive technological nature of it, but that also seems the reason they did so. Methinks it's a case of using cool technology because one can, even though it doesn't produce a more convenient result, however cool it might look.