This is an interesting view about why would an Indonesian write in English,
“Why I Write In English” @ Jennie S. Bev typepad blog.

I guess I feel the same thing as to why I sometimes write in English, even if rarely full-English, but couldn’t really answer when someone ask me why, not until I read the entry.

Here’s a quote from the entry :

I prefer to be seen as an equal conversation partner, which cannot be achieved if speaking certain Asian languages

I’ve been looking for the words to describe it, and “equal conversation partner” fits perfectly.
I mean, you can write without the need to worry that someone older or younger consider you to be rude or dictating because of the word being used to address them.