Being a flat 2/4 means it's quite good at holding the ground. "Drawing a card" every now and then also very good value in almost every matchup. The lifegain in this metagame is not irrelevant. Synergizing with Sylvan Library (which we want to play anyways) is also top notch.
All of these things make me want to play Courser.
I Zenith for one when I'm behind on lands or need to hold the ground against Burn or UR Delver. Courser is a good mid-game stepping stone to the late game 9/9 Knight plan.

