Guild Wars 2

I am kind of confused on how to use the crafting backpacks or what they are used for. All I saw was “Using this as a crafting ingredient will destroy any upgrades held within” which seemed worrisome.
Thanks for any explanation.

It means exactly what it says.
If you use it as an ingredient to craft another backpack the upgrade(if any) will be lost. You could avoid it by making a second backpack for the ingredient but most low level upgrades should be cheap anyway.

…but what good are the backpacks? Just like an normal back brace armor?

Also do these count for the Fashion Forward Achievement?

They fill a gap. There were several level ranges where there were no back item equivalents. As mentioned in the blog they are also meant to show off your progression in the various crafting professions. The max level one you can craft is also the cheapest way to get a back item with an infusion slot.

Since they unlock skins in the wardrobe they should count for the fashion achievement. I haven’t checked.

For the most part, there werent many backpacks as you level. I used the level [something really low] backbrace from a very early story reward all the way through 80 when I finally got another story reward one. These backpacks would have been great leveling up.

As for the upgrades, just dont put the best thing you can find in it if you dont want to lose much when you upgrade it. You should be getting gems and materials easily enough to make 1 upgrade for each one just from farming nodes.

At level 78 (the highest backpack and exotic) with a maxed rarity level 65 upgrade in it, these backpacks actually have higher stats than a level 80 exotic with a level 80 gem in it. They also have a single infusion slot. So they are a pretty cheap decently statted piece while you work on an ascended one.