The galactic barrier surrounds the galaxy, it doesn't just exist on the rim.Trek has far worse continuity errors including travel times to the center of the galaxy and the galactic rim being commonplace in TOS/TAS and not so in DS9/Voyager, and SNW's establishment of biofilters muck up entire movies like Wrath of Khan (why didn't the biofilters catch the ceti eels?). At least with TNG maybe the new characters are just ignorant about holodecks.
People around 2009 treated 3D movies as this strange new thing thanks to Avatar but the tech had been around way before that.
Also, biofilters only detect what they're programed to detect.