It's not surprising why many are concerned with strict Role-Playing so much. No one wants to see "l337 d00dz" running around with names like "1mmag0nna Pwnj00", talking about being wasted in the main channel and calling everyone "n00bz".
People who want to avoid that usually flock to games or gaming servers that have an emphasis on Role-Playing. And that's completely understandable.
However, it also must be realized that there are some very uptight people in the Role-Playing crowd as well, who will try to report you for playing a not-so-nice character.
For example, if I am Role-Playing a character who looks like this (not necessarily my favorite type of character, it's just for example purposes)

And talks like this
Cower, brief mortal! Your pathetic human mewling matters not! Muahahaha!
No one can seriously expect me to say things like "How can I help you, dear sir?" instead.

One the other hand, if someone doesn't speak a very good English and responds to me with
I not understand. My English is not so good. Really sorry.
I won't bash them for not being an ideal Role-Player and let them be. Might even help them out, if they ask politely, and if I have some free time.
If they say
Sorry, I'm trying to figure out a quest right now
I'll simply say [no problem] and let them be.
What I'm seeing here from different opinions posted is basically that people don't want "l337 d00dz" or the uptight RP'ers, which really are just extreme examples of bad Role-Playing.
I think we basically are all in agreement here.
