Not sure if you understood me correctly, what I wanted to say was that what the install button currently does is work in the way you described above, not that it's actually using the subscription system.
Having said that, I don't understand what you mean by disabling a non trivial feature.
Repeating myself, this won't be implemented until 3.5 and even then we have other features that will most likely have a higher priority.
I'm sure we'll reconsider your suggestions at a later date, but at this time it's not really an issue.
Still, thanks for your comments/input.