I don't see what the big deal is on the inseam stitching. It is really not that obvious. The thread isn't even that thick! If you don't like it that much, take a marker and darken the stitching. No one will ever know. I think it is cool though! Its just a small detail that separates Momotaro jeans from just about every other Levis repro brand. It is really not bright, and as the indigo wears around it, it kind of colours the thread a bit darker anyway.
^ BiG do have those white back stripes in 14oz... or at least they did a few months ago. i know cuz i tried them on. as for context measurements on the 15.7oz, they're O/W. however, maybe they're just different model/cut altogether.