[MMM]

I am thinking the "anxiety" experienced is more by the parents or more likely grandparents who see their child or grandchild as "slower than average" when they are simply processing (and cementing) a larger amount of information that in the "end" (say at kindergarten or 1st grade) establishes them a BETTER communicators than their peers because they can do it in two languages...

and beyond simply two languages, but two mind sets. One of the biggest hurdles of Japanese language study, for English speakers, is being able to erase what you know about how language communication works, so a certain degree, and allow your brain to accept systems that seem illogical. (i.e. present and future as same verb tense). If your mind is exposed to two (or more) communication tracks at youth, imagine how open your brain might be for other things in the future.