It seems like wherever they sourced the bags to be sewn together had some inconsistencies. Big Hyzer wouldn't have known unless they pulled out every bag, loaded them up with discs and tried to use all the features.
Likely it made more sense to them to get the bags in and shipped out asap to the preorders. I'd expect better QC with a regular stock of bags in the future. But that doesn't necessarily excuse a lack of it with preorders.
Of course, it's been stated in practically every bag thread; that's the risk of preorders in general. You can either take the risk or wait for a second run, lol.