Now a "day" for Allah is a very long time: In Quran (22:47, see also 32:5) it states: "a Day in the sight of thy Lord is like a thousand years of your reckoning.” In Quran 7:54 we read that Allah took 6 days to create the heavens & earth...

After noting that Quran 36:82 indicates that "All He needs to do to carry out any command is say, 
'Be,' and it is," we can ask:
Why did Allah refrain from using his magical powers to instantly create the universe?