In fact his display is at about 100 ppi, which is not bad at all.

Using the "Is this retina?" page, OPs monitor becomes "retina" at 86cm. And looking at his setup, that's probably how far he sits. His screen is way back, beyond the edge of the desk.

The MBP screen has 220 ppi but it is designed to be viewed from much closer.

As for the backlight, then again, it is relative. In a well lit environment like in a typical office, it simply matches the ambiant light. In a dark room, you'll probably want a dark theme anyways.