thatd work if it wasnt for (some) settings of course. but even then, image and then update /etc and friends and done but here we are
What you describe is the cloud image. You can dd it to your hard drive and it should work as is (initial password will be displayed on first boot).
As for Debian, the slowness comes mostly for fsync calls I think. You should be able to use eatmydata to avoid this. See: https://people.skolelinux.org/pere/blog/Quicker_Debian_insta...
Yeah, I know, my point is that ordinary installer should do the same with ordinary installer UI rather than trying to install every deb package over and over again, running its pre/post scripts, etc. What's the point? It should be deterministic anyway.
My guess is that nobody really took the time to optimize it. Installation is only one-time procedure and even it if takes a hour, who cares.