There are so many situations where having a shorty will give you an almost guaranteed win in a gun fight. That last headshot demon enemy is hit for 140? The shorty will kill them from a good range before they can even react. Playing near/inside smokes? A shorty will win you that duel 90% of the time. Know the last enemy is in Uhaul on Bind or right around the corner from you? Jump peek them
with the shorty and 2 tap them in midair. It doesn't matter how good their crosshair placement is if you are literally flying above their heads - you will likely win that gun fight.

The gun cost just 150 credits and has so many common situational uses. If you can afford it with your eco, having a shorty is a massive advantage.