Personally I see the requirement to learn Arabic as part of Islam is nothing less than confirming what I've always believed; Islam is a form of colonialism that conducts cultural genocide by stealth. No one questions this genocide because it is part of a religion thus making it immune from criticism.
Yes. On the one level, it made sense to me that you should learn some Arabic or learn to read it to read the quran, the way a Jewish kid learns Hebrew, but then I realized, you know, most of my Jewish school chums learned enough Hebrew for their Bar/Bat Mitzvah or to say some prayers, and then they go on being Jewish and learning Judaism without people saying 'You don't know enough Hebrew and you don't really know what you're talking about' or something. Well, this is probably also because Judaism allows for Reform, Conservative, etc. - the different schools, but Islam claims not to have any of that.
Whereas for us, there was always this thing where you never know enough, no matter how many hours you sat there with your legs folded underneath you, studying and studying. When I found out that there are people, especially in the Subcontinent, that study for years to read the quran in Arabic and they don't understand that and yet they were praised and held up as examples of 'scholars in trainiing,' it really bothered me. You would have a 16 year old haafiz - mashallah - come in to the masjid and he didn't understand a word of what he was repeating. But he had perfect tajweed of course.
You were never proficient enough in Arabic to say or question anything about the deen, that is always the excuse. Islam is universal for all peoples and times except that it isn't. You can't have quran in English or hadiths in English or fiqh in English, and ditto for Urdu or Punjabi or whatever. I have friends that spent several years learning only Arabic non-stop, all day everyday for two or three years, and at the end of it they can conjugate verbs or diagram sentences like nobody's business, but they can't talk to a regular Arab person or understand a news cast -- and of course, they're not good enough to interpret quran or a hadith or question some fiqh ruling.