interrupter brakes... for more braking positions in order to inspire confidence in the less skilled rider.
Grrr..
They are extremely useful for anybody who has to use their brakes frequently (urban riding especially).
And yeah, the cable just passes through. It should have zero effect on the feel of the braking. If anything, it should result in a tiny tiny tiny tiny decrease in cable friction, since there is about 1/2" where the cable is 'free' as it goes through the lever