It's interesting when players yell, scream, and get emotional.
It happens even more so in a team environment like college tennis, where there's a social element to impress your teammates - to appear as if you're trying really hard or that you care. I find it strange and misunderstood.
Roger and Rafa don't obnoxiously scream or pout... I'm sure they'd do it if they found it beneficial, but nobody questions Roger's effort if he's stoic after a loss.
Instead of wasting energy in senseless emotion, they focus all their energy into playing great tennis. Not to say Roger and Rafa won't reward themselves with a fist pump, but it's genuinely felt emotion and not a front to cover up an insecurity.