As a skinner and leatherworker, I do find the scraps irritating. But I think it is more psychological than anything else, as the concept takes you back to beginning skinning where you took scraps and turned them into light leather.
I think if they took out scraps, and replaced them with 1 knothide skin, with an occasianly 2-5 knothide drops as you skinned higher level mobs (and adjusted patterns accordingly), I think people wouldn't be as upset about skinning, even though the amount of skinning per crafted item would remain the same.
Anyhow, on engineering, it has always been I think about play style. If I leatherwork, enchant, jewelcraft or smith, I create items and either equip them or sell them, not really thinking about them much further.
Engineering however is an active profession, which essentially increases your "castable" options and thus adding complexity to playstyle. I don't know how many times on my warrior Grimgear I have kicked myself after dying or a group wipe when I realized I could have used so-and-so engy item to turn things around, probably because I was focused on using warrior abilities.
I think engineering has a lot to add to non-healing classes, esp warrior and warlock. But it is a profession you do because you want to increase your play options, not to make a profit from. If you find it fun, don't drop it. If you hardly use it to your own benefit, pick up a profession that will benefit you.
