You're not wrong to be unhappy any more than you could be wrong to be thirsty. The question is whether you decide it's worth doing anything about this.
You might want to wait until after the holidays and then suggest to his parents that for financial reasons you would like not to exchange gifts any longer. They might be relieved.
My MIL gives me absolutely generic gifts because she has no idea who I am. In her mind, I'm just her son's wife, and because she's been so enwrapped in her own neuroses, she knows nothing about me. My gifts from her always come from the "holiday gift" rack at the front entrance of WalMart.
My husband received a really generic and expensive gift from his father once. It was nice, but it wasn't *him*, it was just like his dad was watching QVC and bought something because he was running out of time. It stung him. And it hurts me, on the sidelines, watching my husband attempting to like this thing his father sent him.
So honestly? I'd be proactive with them and discontinue giving the gifts. If you want, you could even say, "We fully understand the thought you put into our gift, but because DH couldn't eat any of the candy or cookies, due to his serious medical condition, we donated it to a local food pantry. They were very glad to have it, of course, but we felt it would be better just to discontinue exchanging gifts."