Skinning is far from useless. At your level, you're probably getting a lot of light leather. I find that this sells relatively quickly at the auction house, even though it doesn't sell for much money per stack. The trade-off is that skinners can get leather from many of the mobs they kill (except humanoids, with exceptions, birds and spiders). Thus, you make up for the low return from each stack by getting and selling many stacks. It adds up over time. At lower levels, the production professions (alchemy, engineering, leatherworking, blacksmithing and enchanting) are more of a money sink than a money maker.
Also, at later levels, yu'll find that different leather may sell for a better profit than it currently makes you. See what sells well on the auction house. FOr example, I found that hides rarely sold on my server, while black dragonscale made me a pretty penny,and even rugged leather sold for a couple of gold per stack. Multiply that by the number of stacks you can get while exping, and it can amount to some pretty gold lining your pockets!