The temperature of the diode will change right along with the temperature of all the other hardware, it's not as though you'll go out of your way to get the diode heated up.

The way it's drawn is not the way it is built, the diode would normally sit near the computer end of things, not right on top of the sensor.

The thermal drift of the other circuit is at least as large as that of a diode at room temperature, probably a whole lot larger.