I find most people continue to ignore the bars unless they're the supporting role in an endgame static where people specifically tell them to look out for it.
The only reason I can think of for this is because there's no legitimate support role, just DPS classes with some support options. So that Ninja isn't going to think about looking up at a bar, especially since he's had a year+ of motion training to only respond to chat when asked for a goad.
A bard MIGHT be a bit more helpful since they're sometimes (rarely, but it happens) looking at the healers MP bar. They may glance at the TP bars as well.

If we had actual support roles with classes that aren't designated to add damage from themselves, then maybe we'd have a quicker turnaround on the random pickups responding to low TP issues without prompts.
But that's likely not something going to happen.