Problem is, getting to half~ TP is normal in a standard rotation for my Monk and Dragoon. Ill get to to that halfway point and then hit Invig and suddenly I'm full TP again.

I don't know what you may or may not be planning, and i don't want to waste a Goad on a DRG who hits Invig at exactly the same time.
Sure, i CAN see it, and on my AST i will throw Spire on whoever has the least TP (usually the Tank, they don't have any TP restores) but generally a DPS can handle their own TP regen. So while i can see you getting low, unless you tell me you can't fix it yourself, I have to assume you've planned around it.
Its certainly handy to see, especially on my BRD and MCH since i know when its safe to turn off the Regen. Just because MY TP is full doesn't mean everyone else is also full and that Bar lets me monitor it properly.