It's just a nice touch to SoloQ-er if Riot add this, Phoenix got his watch out flash thing Viper should have this too, it's especially useful if some dude play Viper and doesn't talk like at all.

But if a shout is to expensive to use the actor you could use the good old ui, share her low fuel ui with other agent.

Edit :

Wow I didn't know that Viper wall makes a different sound cue when it's low but IMO the sound cue sound is barely different from the normal sound and with how popular this post has gotten I'm not alone in saying that this should be made more obvious and I feel like the distance of the sound cue should be increased since it's rather small.

And as for you saying "Just use comm" Pls read the post, it's not about me not using comm but negating bad teammates that don't use comms impact on my and many other games, and not getting harassed by other for your voice.