Never had a problem with Steam's use of resources or game loading times personally. Admittedly, I have my favorite games bound to the extra keys on my keyboard, so launching them is perceptibly instantaneous. Naturally, PC is a very varied system, so I understand that not everybody is running the same environment.
If you want to cut down on loading time (and have already lowered the game's settings), you can shorten it a little by adding "-novid" in the launch options. It's not a massive difference, but if you like shaving off seconds, it works a treat.
Beyond that, you're not going to have any luck getting Valve to publish one of their own games outside of their system. From Valve's perspective, it would only result in losses. There are alternatives of course, and it seems as if Icefrog intends to support wc3 dota for some time, and you don't need Steam for that.
Though your signature says you no longer play dota, so I suppose the entire thread is a nonissue.
Ultimately, however, your topic would be better discussed here: http://dev.dota2.com/forum.php