By moving the installer scripts out of the base virtualmin package, you could update the scripts and roll out the update, independently of the virtualmin update.

This might help keep the install scripts fresher and more quickly up to date, without being tied to bugfix releases.

Not being familiar with the code, I don't know how intertwined the scripts are with the base virtualmin code, but it sure would be nice when updates are late or broken, to get them fixed quicker.

Yes, Jamie has been working on that for some time (since about 3.50, I believe). It's a relatively big project, but should be in 3.54 or 3.55.