Using angle grinder to shave wood?
You can use it, they work for coping and other sundry shaping. Then again, the fact that you can make a statue with a chainsaw doesn't mean that every carpenter ought to have on in their toolbox. A plane will give you a much flatter surface and probably be just as quick. I would suggest avoiding the grinder unless you can accept a wavy surface, since it will be difficult to keep the wheel flat and wood abrades much more quickly than metal or stone. 

Speaking of chainsaws, I would suggest avoiding the chain-wrapped wheels for grinders in their entirety. I've never heard anyone suggest that they're a good idea. If you haven't seen them it's a grinder wheel with a chainsaw blade around the perimeter for sculpting wood. 

A better solution is one of those abrasive flap wheels which mount sandpaper flaps to a grinder disk. It's not a replacement for belt sander but it's an economical solution if you already have a grinder.