There's a limitless number of commands that can be given through voice chat, and it'd be insane to try and get a signalling system to approach it. My most common command is "Don't shoot the mortar yet. Hold it.... hold it...... go go go!"
But back on topic, it'd be nice to be able to say what you need to, regardless of where you're at. If I'm on the gun, or fixing something, and I want to tell someone else to man the other gun or just a gun, my only option is to shout that -I'm- going to man a gun; which is the opposite message of what I want them to do. Same with engineering. If I'm fixing the balloon, and the hull is about to go down, I want to shout "Go fix the hull". My options are "I need help fixing the hull" or "I'm going to fix the hull".
I know that in an ideal situation, the captain is giving the orders for who to go where, but if things aren't ideal (the captain is new and you're trying to help organize players) you don't have a lot of options.
Personally I don't mind the filter. Generally speaking you don't need to send that many signals that frequently. I've only hit this filter once, when desperately trying to get my captain to turn to face the enemy. And if they're not going to listen to the first signal, they're not going to listen to the rest that you try to spam them with.