At Lvl 35 killing a Lvl 4 beast gave 1 Exp, but the skinning still 10 Exp. So resource gathering is still helpful later in the game - every Exp counts!
And there are incentives to level the crafting skills with the keys needed for expeditions: one you can get as a quest reward, afterwards you need to craft the key yourself. With being "Bind on Pickup" (the material for it is BoP, too), players are either dependent on having a crafter in their team or they have to craft the key themselves. No players that only log in to run the dungeons/missions ;)
On what server did you play? Because I experienced it totally differently.
For example, this is a material required to make the orb you need to enter an expedition. I can sell/buy it in the Auction Hall. It's not BoP.
Skinning itself gives you not as much XP, but leveling up Tracking & Skinning gives you a lot more. Check out these screenshots...
Killing: 118xp
Skinning: 22xp
Leveling up Tracking & Skinning: 466xp
606 xp in 2 minutes.
I think it was for the lvl 35 expedition - some item "Stone ?? Orb", to craft it at the stonecutter a number of the shards that drop when you close a portal are needed, and something called "? Heart", which must be crafted, too.
Sorry, I didn't see the English terms, only the German (where a lot of items aren't translated yet, but have names like masterpiece_40_armor) and can't look it up, since it doesn't run on my computer.
The Orb and fragments are BoP, but not all materials that you need to make it are.