While I'm sure there will be more guidance on how they define "appropriate," it really opens the door for a lot of inconsistency with how it's enforced. One lead may say that a particular tattoo is okay, while another may not. And unlike hair and nails that can change from day to day, a tattoo is going to remain the same, making the inconstancies even more pronounced. I feel sorry for the lower and middle management who are going to have to enforce this on a daily basis.
Additionally, it represents another instance of placing the individual CM's personal style ahead of the larger designed environment that they're working in. Whether you want to say that employees are wearing a costume to play a role, or wearing a uniform to look uniform, the purpose of the matching outfits is to make everybody look the same. But when tattoos are introduced, with designs that may or may not fit a particular location, a lot of the carefully-constructed imagery can begin to unravel.
As much as Disney's social media likes to proclaim that "every role is a starring role," most of CMs are supporting roles at best. If a theme park were a film, many roles would be considered extras, filling in the periphery of your experience, largely making things happen without being the focus. With few exceptions the starring roles would be in the entertainment department (assuming that individuals can even be the stars, rather than attractions and spectacles being the stars), which already has different guidelines based on filling those particular roles. I understand the difficulties of hiring and retaining a large workforce at Disney's wages, but this seems to be a dramatic departure from policies that they've operated under for 66 years, and it's unlikely they'll ever shift back.