Some of us have poor connections. In addition, the 64bit installer is too large to download as a single exe file (being something along the line of 4 gigs). If you don't have fast internet, this can take hours to download at a time. The problem is that at 3.9 gigs and ~600 megs the first file will frequently time out on our connection (it takes about 10 hours) because of how long it takes. Breaking it up into two similar sized chunks (~2 gigs for current downloads) would help aleviate this since a junk file that cancels halfway through woudn't take as long to download. Even better would be breaking it into 20 pieces (which you could mass download or download specific ones that are scrap) or releasing a torrent download (which would significantly reduce the Autodesk server costs).
Having to set it downloading after work and then hoping it doesn't get disconnected in the night and having to go again the next day because of how large the individual file is and hoping it works that day is not good. It's needless headache.