When I got my PRS-T1 for Christmas, I did not really see outright, the benefits of rooting my PRS-T1. My wife's Evo3D and my OG Evo are both rooted, and I've rooted numerous phones, so as far as that goes, rooting is a tremendous positive. For a simple e-ink device, I just didn't see a reason to do so, that is, until I tired of the limited selection of fonts available in the default reader app, and the lack of a on-screen clock like I had with the PRS-505. So, after only a few days of using the T1, I rooted.
For those of you who don't really see a reason to root, I've attached a picture that shows the before/after of rooting. I'm glad I rooted, and couldn't imagine using the default Homescreen/default reader. I use the Alternate Homescreen developed by mrspacemonkey.