This can certainly be a beneficial practice, and need not necessarily be carried out with anonymity.

One of the greatest thinkers of the Medieval period, Thomas Aquinas[1], honed this skill to a very fine point, and even in his own day was regarded as being able to articulate views which contradicted his own better than those who argued the opposing views in the first place.

His best-known work, wherein you can see this skill at work, is his Summa Theologica[2].

[1] http://en.wikipedia.org/wiki/Thomas_Aquinas

[2] http://www.newadvent.org/summa/1.htm

[&] http://en.wikipedia.org/wiki/Summa_Theologica

AKA "trolling".

Is it trolling if you are arguing the opposite of what you believe currently in a sincere non-inflammatory manner?

It is because you don't believe it and you're misleading people about what you really think.

Yes, but isn't the point of it all to get to the truth of the matter that exists independently of the debate.

The truth of the matter exists and it's what you really believe. Playing around with contrary viewpoints is just childish.

Why be so arrogant to think you're right and just have to convince the other person? Are you really convinced you know everything there is to know about the issue and can't learn any more from another person who doesn't agree with you?

etc...

No, it's called playing devil's advocate.

The best version of this is called "steel man-ing", as in creating the opposite of a straw man.

No, AKA "the socratic method."

i find it easier to start with a neutral view and then research a topic before arriving at a conclusion. time considerations aside, coming to conclusions via thorough research about even mundane topics is a great way to practice/utilize critical thinking skills.

trying to argue for the "other" side can get quite complicated for complex topics, like religion.