All 5 of my horde shammies have at least (425?) engineering for the rockets. Five flame shocks with rockets macroed is usually instant death. My solo mage has also had engineering since I started him in vanilla. It's never been a profession to make money with, it's more of a 'fun' profession. Thanks to the parachute cloaks, my shaman can do the 'slowfall-boom' that my mage used to do in TBC.

It's really your choice. If you want to make money, eng is not for you. I like it because of all the gadgets you can get. The possibility of screw ups make it even more 'interesting'. I remember in vanilla my mage was making a bomb (or something, I don't remember), and it blew up at the anvil, and killed my mage. It was amusing.