So you have to trust the exit node to not do anything with your data (since it's unencrypted at that point). Also, because of this, you don't want to host a node from your home as all of the exit node's traffic will look like your own traffic to the ISP (meaning any illegal activity will look like it's coming from you).

So basically it turns you (if you're an exit node) into a VPN provider with all the accountability yet no responsibility and no insurance. Sounds like that could be a recipe for disaster.