Because he works "from coffeeshops and client meetings pretty often, so it’s nice to have a reminder of my remaining battery power to know when I need to plug in". Didn't you read it?

I agree. There is a lot of screen estate these days, even on laptops, so why not save the shell window for stuff that is actually useful in the shell window and that can only be displayed in that window?

The current git branch makes sense, as does the current directory, but I'm having a hard time finding the point in anything else cluttering my shell window.

because his command prompt runs so many extra commands and causes so much disk activity every time he hits enter, it wastes battery quick enough that he needs to monitor it.

I hope he also has the number of unread emails in there.

If you've got all your space-wasting menu bars on auto-hide and are just using Gnome-do/Synapse/cmdline/etc. to run stuff, it would be useful.