Tattoo Artist is currently important not because of the formulae, but because it's the most expedient route to crafting magic tattoos at all.
Crafting a magic tattoo requires the ability " to craft magic items and have a specialty in tattooing." Previously, you could do this by taking both the Magical Crafting and Specialty Crafting skill feats.
Tattoo Artist allows you to craft magical tattoos with a single feat. So you can use Tattoo Artist even without being able to take advantage of the free formulae. In fact, it's the optimal route to crafting magic tattoos.
Although there are no formulae that match your needs now, it's possible this is "forward compatible" with future releases. Not that it helps you today.
Potential GM Advice
At my table we have a player making extensive use of magic tattoos. I treated it like an alchemical creation, letting them pick from the table of alchemical items (subject to a GM sanity check). Although this content has only been out for a month or two, so far this has been balanced at our table. We aren't serious character optimizers though, so your mileage may vary.