I think I've been in the "white collar" industry a bit longer than you and you're not entirely right. Perhaps your field is slightly different but frankly a tattoo tells me nothing about the person's work ethic and ability.
Correct, but there are also such things as first impressions, for both the employer and the customer. Get a tattoo by all means, just make sure it is something you can easily cover up.
I worked for a company that had another firm in to do a computer roll out, and one of the guys had quite a few tattoos, he had to wear a long sleeve shirt under their corporate polo shirt to cover them up.. in the middle of summer... in a building that didn't have great air conditioning.
A tattoo in and of itself isn't such a rebel thing these days, but where you have it, how many, how big etc determines how acceptable it really is. The little butterfly on the ankle...meh... the skulls and guns & knives down your arm... umm... not so appealing