What world do we live in where even the smallest or most charming tattoos can be perceived as something so discriminatory that is has to be argued about? You are not in charge of somebody else's own skin.
You have no right to tell people to not get a tattoo because you "don't like it".
People, who have tattoos have chosen to do so looking down on them because of the decisions they make is bullying in my mind. Also, to look down on them is wrong as you are judging them just on appearance where you should be doing so on their personality.
If you don't like people looking down upon you then why do you put yourself in that situation of possibly being looked down upon? Doesn't make sense to me. You don't have to keep getting tattoos. I do agree that people shouldn't judge a book by it's cover though. It just shows that people really do hate.
Many cultures have different views towards tattoos. For example, the Chinese (and some others too) used to tattoo symbols onto criminals in visible places (e.G. Cheek, neck) to represent the crimes they committed and warn people of them. Thus, to the Chinese, tattoos are a symbol of crime and shame.
Some people link tattoos with gangs or criminals and while not all people who have tattoos are gangsters or criminals, many criminals (the brawl-kind, especially) do have tattoos.
In some regions, a lot of people who do labour-intensive work (e.G. Truck drivers, construction workers) have tattoos, thus tattoos are linked to "non-intelligent" jobs and the lower class.
While I do not support any kind of discrimination, I think that due to the traditional or cultural values having tattoos possess, we should not be too harsh on such people.
Contrary to popular belief tattoos carry their own meanings which means that functionally speaking they are not supposed to be for decoration. To that end it is obvious why people judge people who write pictograph messages on themselves. Of course no one wants to be judged wrongly nor read wrongly but that's the danger of tattoos themselves:
They are pictographs oft used to send a message that is not supposed to be interpreted by wide swathes of people.