Well, it's better to have them decoupled. For example, let's say you're trying to watch The Godfather in French, you wouldn't want the scenes in Italy to have hardcoded English subs.
I did the same with The Wolverine. I thought the non-subtitled Japanese parts were an impressive artistic choice. I didn't need to know what they were saying thanks to tge acting and other context clues.
It wasn't until a couple of lengthy flashbacks that I started to suspect something wasn't right.
the first subtitles are almost at the very end of the movie, so it was too late to bother. Also, most of us watched it before, but man was it a letdown.