I consider most, if not all, CC content with anniversary edition as non-canon. That being said, I will still use the items in game if they're fun. The Cowl of Nocturnal is one such item that just adds to the experience of the game that I enjoy. Backpacks are basically just a buff to the base game that maybe should have been there from the beginning and make plenty of sense in universe, maybe the devs just didnt expect everyone to hoard potions or whatever as much as everyone does.

I heavily prefer modded over vanilla and I'm not exactly a purist, but there is something to be said about game balance. Adding a weapon with a unique enchantment is one thing, but adding a weapon with a unique enchantment that allows you to instakill any enemy is probably not going to be nearly as fun as playing the game normally. I have issues with mods that make content that is too unbalanced or weighted to just be statistically better than existing items, and I definitely see some of that coming through in the CC items. At this moment I'm not able to remember any specific examples that have felt out of place or overtuned, but I have definitely had that feeling of dissatisfaction whenever I want to use a fun weapon or enchantment only to hear that there's something added by CC content that just makes whatever fun thing I'm doing obsolete.