When a Ninja is focused on keeping 2 DoTs up, TA up, Huton up, and possibly Dancing Edge while also not screwing up their rotation, then they may not be prioritizing Goad, especially since they have no TP visibility.

Another thing is that sometimes the NIN does use it at random due to lack of TP visibility, but then the tank asks for it when it's on cooldown and then doesn't understand why they didn't get it.

If you need it, ask for it. Communication is the best way to make Goad effective. Otherwise, you'll probably just get it when you get it, but don't expect it to be your TP savior all the time. Goad is a luxury ability - content can be completed without it, it just makes some situations a little more comfortable.