If the running-apps-on-drive0 problem could be solved, the rest is trivial. You could even code a complete application installer entirely in the DOS batch language with a little help from FTP.exe.

I guess we just have different ideas as what the appropriate scope of a solution is then.

The difficulties people have encountered using DOS batch scripts / FTP scripts have shown (to me, at least) that is not really an adequate solution. (Here is one of the many examples of problems that could be avoided.) Things like parsing the manifest file or saving uninstall information or getting user input for dynamic installation parameters or editing the player's config.ini are all unsuited for such scripting. Not to mention that DOS scripting would completely cut out the non-windows users.

I'm not saying that the idea is (technically) very hard to implement, but to write the application the way I envision it would take me more than what I would consider a trivial amount of my time. And I don't think writing a crappy one provides any worthwhile benefit over the scripted installers that are being used now. That said, if anyone does have the time available to code up a decent one, I'd be more than happy to use it