1) to limit the control the character has over a power that can be turned on or off, and
2) to represent a power that can never be turned off, because it is an integral aspect of the character.
This post is about the latter.
For example, the Hulk's growth can't be turned off, because his huge size is simply part of his state. I mean, a Size Change-suppressed Hulk is a green guy who looks silly and is absolutely not the Hulk.
Ergo "Can't Hold Back (Always On)" is both a limitation and an advantage. Now, this doesn't change the cost, at all, because there are lots of times when a Huge Giant would benefit from being able to turn off the power, but can't, even though it's nice the power can't be suppressed.
That is to say, that "Always On" is a subset of "Can't Hold Back," with the additional qualifier that "Can't Ever Turn Off," and also "Can't Be Suppressed," and "No Change to Cost."
Model unknown. I found the picture on Pinterest.
