I almost bought Bravely Default for download play today, before realising I was almost out of memory on my 2GB SD card. I decided I should probably google and find out how big the game was. It's, uh, about 3.5GB on it's own (25K blocks). So yeah, I might just wait until I can get a physical copy (or a bigger SD card...).
Also this doesn't even consider the download time. My biggest game is about 4.4K blocks and I think took well over an hour, probably closer to two, to download. So this would likely take the best part of an afternoon.