The tubing allows variable brake application easier. Shorter tubing will make the brakes harder to modulate, it will be like an on/off application almost. Longer tubing will make them more progressive through range of servo travel. On a 1:1 car it's like having a spongy brake pedal with lots of travel vs one with a very firm pedal, spongy pedal (long tube) you have to move farther to get braking increase, firm pedal (short tube) you just have to increase the force instead of moving as far. I prefer the longest I can use to make brake control easier. Too long will not allow full release nor adequate braking, it's a balance thing for sure. Take them out and put washers or solid tubing in place of it if you want to see an extreme example of it's effect. That would be hard on servo gears though
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