There are no limits on downloads through Amazon. When you buy FFXI expansions, you're really just buying the activation code. Even if limits did exist, it would be entirely possible to torrent the game simply because you can't do anything with it until you actually pay for the game.
As far as the simple installer, it is really annoying how SE has everything setup, but I think there is a lot more involved in switching over. It already takes 10? hours to download just the updates and that would be even longer if significant content were to be added. I believe this is because the updated downloads files one at a time from a single location- another reason why update days are so awful.
Fortunately, it seems that SE has already implemented a better update process for FFXIV, so they are not completely left behind. Unfortunately though, it just might not be worth the time/effort to change it for FFXI.
Draw My Character Vlor!
Edited, Feb 25th 2013 5:20pm by xypin