The Ravens Of Thri Sahashri s also great but the Feth player bears the brunt of the deduction and makes all the spatial choices. This leaves the Ren player with comparatively fewer choices to make during a game. Not a problem, the game runs smoothly but I can see a good Ren playing getting frustrated at a crap Feth
The two roles appeal to different people. If you're Feth, you do the direct action, for the most part. If you're Ren, you influence the action behind the scenes, providing key information that allows Feth to succeed.
It's like the spiker and the setter in volleyball, or the lead and the follow in ballroom dancing, or the soloist and the accompanist in a duet. I believe it's an error to think that one is more important in any of these 2-person cooperative activities. They are just different in prominence, perhaps, and different in what skills are needed.