The idea is that it pulls the TOB back clear of the clutch fingers when the clutch is released, so the bearing doesn't turn all the time, or worse yet not turn and drag across the face of the fingers.
I also find that without it, the exact pedal position at which the clutch starts to engage varies from time to time, which I find somewhat irritating. IOW if I haven't used the clutch for some time (like when getting off the freeway), it will engage closer to the floor than usual. Not really a problem, just irritating that the car kind of jumps forward when trying to creep along with a line of traffic when the light turns green; unless I let it out extra-slow (which means it takes longer to start moving).
PS, this is a different situation (TR6 TOB is supposed to turn all the time), but kind of illustrates that having the bearing drag against the fingers is a Bad Thing. Supposedly less than 5000 miles on a new clutch.