I have the same finishing detail on mine (if you look closely it is professionally finished). if it was finished as per the the other internal edges it would possibly be too stiff? and slightly uncomfortable / awkward against the upper back and shoulders?
I've worn mine (J84) on a few errand runs these last few days and I'm really happy with it. I was a little curious about the sizing but glad I stuck to my normal size; if I went down a size it would be too short. i'm mostly wearing it popped (?) and not zipped. the temp has been fluctuating between 10-20c here (!) and it's kept me comfortable in all of that whilst walking / casually cycling around. the pockets hold a phenomenal amount without it looking like your colostomy bag needs emptying. the TensionZip pocket entry is super useful when faffing around at the self checkouts and easy to close / access whilst on the bike. the collar sits nicely when the jacket isn't fully fastened - mine seems to sit closer to the body than the Mothersite pictures suggest (it looks like it's floating in at least one of the shots). and i love the hood... maybe the novelty will wear off, but it sits on my peanut head rather nice.
marginal gains overall, but that's late stage capitalism life, right?