On a x7 skill proff rate, most of the time you end up with extra materials (because you level them 7 skill points at a time), that you either vendor, store on your guild vault or if you're not bothered to keep it on the Auction until it sells.
Now on a x3 skill proff rate, how do you imagine having more mats? where is this extra supply coming from? you assume people are going to go out of their way to farm more materials than they actually need or that they are somehow gonna use less materials to skill up?
Again, players are inherently lazy, they chose neltharion because neltharion was appealing to Lazy players, (heck I don't play on x1 rates for a reason) and ok you can try to disregard my opinion because hey It's only my opinion and you can say my opinion is not the Community's opinion. But I bet you my soon to be halved gold, more than 50% of the server share's my opinion. and that's from a player that hates leveling, hates to level proffessions and has had to level 5 toons with not all of them having proffs, because in the end, people who play Neltharion want a lazy experience, not a blizzlike or sorta blizzlike experience.
I dunno if you've had to actually level your proffs, but you should really do a sort of announcement on Neltharion during peak times and tell people to whisper you "1" if they are against your changes. Then you'll see true feedback.