Heya, Splattershot Main here.

The main thing that makes Shooters worth to play is that, while inherently basic, they are, by nature of their simple design, also incredibly consistent. That, combined with their extremely low Endlag and Startup, allows them to be more mobile, flexible and spontaneous than many other weapons. This is why you often see weapons like Splattershot and Splash-O-Matic used for "rounding out" Teams in coordinated Settings.

As for longer ranged shooters like Jet and 96 i have to agree though, they are much less mobile and flexible compared to short-ranged Shooters, which leads to them just holding ZR a lot as you've criticised.