Listen, I have no issue with onsen having a tattoo policy — around 50% of onsen these days allow tattoos. My issue is that their no-tattoo policy is not on their hotels.com listing, and the rather rude manner in which the information is communicated to customers via an illustration conflating people with tattoos and drunks. Oh, and of course, the “bathing tax” which we had to pay despite not being allowed to use the facilities.
Luckily, we were able to find numerous nice, clean, and reasonably-priced onsen in Kyoto where we were welcomed.
If your hotel has a policy that will make a good number of people feel unwelcome, it needs to be on your hotels.com listing, not buried on their own website.