Okay, while I demonstrably think Rescue has valid uses—as I have detailed in this thread—communicating that you think a tank is moving too slowly is not one, at least in my opinion.

I have met very few tanks who would not be annoyed by that. Plus, we have a more effective way to reliably communicate that bigger pulls are desired: the chatbox, where you can type "hey, you can pull bigger than this" or whatever. Or heck, if you don't have a keyboard handy... like, my solution as a healer to encourage the tank that "no, we can go bigger!" is to run slightly ahead of them and then jump up and down a few times. This is evidently sufficient, as like 95% of the time I've done that a tank will pick up the pace and stop playing it safe.

Back when Anamnesis Anyder was current and the mega-pull (i.e., the "pull everything from the second boss to the third boss at once" pull) was actually capable of turning some careless parties to paste (but also was some of the most fun you could have in a dungeon at the time), I'd often pro-actively tell the tank before leaving the second boss arena, "BTW, if you're good with it, I'm up for the mega-pull!" And usually they'd go "Sure, let's go!" and then we did it. Or if I didn't have time to type it before they took off for the next pull and they stopped at the halfway point, I'd step slightly further ahead and jump up and down two or three times and... like I said, roughly 95% of the time the tank would pick up "Oh, hey, the healer thinks we can go bigger" and go get the second half of the mega-pull.

Using Rescue to make that "request" rather than just, you know, making the request strikes me as vaguely passive-aggressive. (Or maybe that's active-aggressive.)