It might be an international site, but it is based in the United States. Thus, English is the primary language.
Why should 90% of members change so the 10% of members(note: guessing at percentages) can use this site? That doesn't make any sense. Just look at AB Kingdom. Forum-wise, it's mostly in French, but there is a small portion that is in English.
Unless you have the power to ban people(thus, being a mod), people are going to blow your "requests" off because they don't really care and they know you can't do anything about it. You can't force people to conform to your standards.
Personally, I try and always use proper spelling and grammar because I find excessive net/text speak to be annoying.
When it comes to smilies, I don't use them because I never think to. Honestly, excessive use of smilies is annoying as all hell, too.