I am far from a guru - but I can tell you that no program or application is installed in /home/user. What you can find in /home/user are directories containing files personal to the user, like your e-mail, your browser details like bookmarks, history and the like.
Hope I added a clue to the puzzle.
Here is why i'm still confused by this. all documents, personal data, bookmarks, email, history - they are all tiny and mostly text documents compared to programs you install. I'm still not seeing a good reason to make the Home larger and the root smaller. In my case, I need the most room for installed programs and less room for other stuff.
I depends on what the other stuff consists of. If it's mainly text files you won't need very much space for it. If it's pictures and music you need a lot more. And if you also save movies and other video files no partition is ever going to be big enough.
Most people need more space for their data than for their applications.
So, the root folder contains the programs, and the home folder contains all the data output of those programs?
Usually, yes. There's really no reason why you shouldn't test an application by installing its executable in /home/<user>/bin or even somewhere else in your home directory, but Synaptic doesn't and, as you know, using Synaptic is the recommended way of installing applications if you don't want to break your system.
Most of the apps you install with Synaptic go into /usr (with their executables in /usr/bin or /usr/sbin); their global configuration files go into /etc, and a user's personal configuration files into /home/<user> (your home directory).
And as having /usr and /etc on separate partitions is not a good idea (uneconomical use of disk space), most apps will be on the root partition ("/"), possibly with some local configuration files on a home partition, where you'll also find most of the output from the apps.