Trope Talk: Superpowered Evil Sides

So, point ny of discussion.... What makes the He-Man/She-Ra Banner-Hulk, Walters - She Hulk style transformations work? What is it that keeps those interesting, or not boring? And in the case of Bruce Banner -Hulk, isn't that a super powered evil side (sort of).

welp, so since you used sequential definition for power creep at 7:07, I kinda have to ask the follow up: would the power creep still be a major problem if the power sequence is an increasing convergent sequence?