While role players are frowned upon in many circles from magic to psionics to tulpas, sometimes it's a good thing. Certain people may like to do so in order to get into the right mindset, a concept very important to witchcraft, and as long as they don't rp for the wrong reasons or by doing wrong things (ex: to say they are more powerful than someone else, to be "cool", to make someone else feel inadequate or unsatisfactory in their craft, etc.), it could be a great way for some people to work better when they do cast a spell and whatnot.
I myself take part in role play forums from time to time and, when it comes to these crafts, I do prefer to feel more "authentic" by dressing, speaking, and acting the part. This should by no means label me as a role player nor anyone else who does such things because if that's all it takes, any witch who dresses in ritual garb (or nothing in the practice of skyclad rituals) could be labeled as such as well.
This isn't to say that role players in general should be welcome, but instead to change people's mindset. It means nobody should discriminate against someone for role playing if it helps them in their craft, and people who do role play should keep it within the confines of their own private practices.
To summarize, role players are not always bad. Role players who take that more seriously than the actual craft and/or rp on the forum or when speaking to other members about these serious matters are. If it puts you in a better state of mind to cast spells, go ahead and put on a wizard costume. They have them in the online shop here. The most important part of magic is the result, not the method. If it works for you, do it, but not in the public eye and especially not here where it's been stated in the rules of conduct that role playing is not for this site.
On Role Players