Can I ask why so many people are against preloading? Some of the people here seem to be acting like that would hamper the development of Dragon Commander. Which is pretty wierd. Granted I know next to nothing about the actual process but I am pretty sure all it takes to set this up is to call steam and sign whatever papers they want.
If you are worried about taking away from dragon commander the game is already way past any serious additions gameplay wise. The changes the beta comes with are mostly but fixes and other changes that don't take significant resources to make.
So why knock that little extra convenience for those without the best Internet connection? If I had the opportunity to download the night before so I can actually play on release is helpful for saving time and boredom. (Downloading something as big as dragon commander means my Internet is locked down for my whole household.)