I think the bad idea stigma stems from people XORing from the same source. That totally is a bad idea, but if two sources are wholly independent, the maximum entropy in the combined systems is maintained.

To the people that just say it's never a good idea and scoff at any reasoning I'd remind them about OTPs. They are a special case related to this principle of XORing two independent sources together where only one input is random and it is proven mathematically to work.