I don't like the idea of using Al Quran and learning Arabic interchangeably.
Arabic used in Al Quran is definitely THE thing to learn, not the colloquial one.
Sahibul Ajrumiah puts it succinctly:
"To free the speech from error and to understand the Quran and the hadeeth"
that's the goal of the Arabic language. Not to MERELY speak it.
It reminds me the classical example of the inability of many Arabic speakers who fail to explain the difference between.
"Maa ajmalas samaaa" and "Maa ajmalus samaaa"
Muslims MUST learn the Arabic used in the Quran. Not the conversational ones that dominate the Arab world. Unless, they want to enjoy, Amr Khaled's lecture. I heard he uses Egyptian Arabic in his lectures, which is good, so that his people can understand Islam easily.
Almost all texts in Islam, including tafaseer of the greats, are in classical Arabic, that follows the beautiful composition of the Quran, in grammar and prose.
Just look at the beautiful stories in Maqaamatul Haririy, which is a highly recommended text for all classical Arabic learners. Or the ever masterpieceful Nahjul Balaghah, a compilation of khutaab by Ali ibn Abi Taalib.
A good test of Quranic Arabic skill is to explain the declension of nakeeri and nazeeri (verses 17 and 18) in sooratul Mulk, why these words ends with a single kasrah.
Maybe Far7an can use his lifeline, again...