Well I think she was doing other important shit. She couldn't go with the ring anywhere for fear of drawing attention, she had her own realm to take care of, etc. Galadriel and her ilk are also only half-invested in the world of men anyway; then can(and eventually do) leave Middle-Earth if they care to. Any aid they are offering is done out of a sense of justice,righteousness, or pity, not self-preservation.
Well, she actually did need to hide. Her ring was still corruptible by the one ring. The only reason it didn't happen before was because the Elves only used it's power sparingly and even in the third age they only used it to preserve their immortality, and slow down the "diminishment". So she actually had a reason to hide, because if the Elven rings were to fall back into his hands, he could use their magic to do a ton of shit, supposedly.
I guess it's some new hipster thing to hate on Tolkien lore, but I think you end up looking pretty foolish nitpicking texts that are the foundation for pretty much every piece of modern high-fantasy you read.
I think it's just the fact that movies emphasize certain scenes that in the book were minor/insignificant elements. Chasing a few orcs off by looking scary in Moria, for example, makes Gandalf not busting out a fireball on them seem plausible. But when everyone is running around fighting for their life, Gandalf not using his power becomes more, and more odd. In the book, this kind of contradiction in character motivation is really very subdued. Especially given that, like I said before, Tolkien goes to great lengths to point out that not all power is just physical. As strong as Gandalf is, he's not going to walk up to an army and win...And Tolkien does convey that pretty well.
In the movies though, with their emphasis on action scenes, there is a problem with the suspension of disbelief that's not really there in the books. But that's what you get when you focus on fights/action as a product of character power. In the books, a lot of the "enemy's" power was him corrupting people, not direct power. Hell, the whole plot of the rings in the book was political/mental control and
notphysical power. In fact, Sauron got weaker from pouring himself into the ring--but in the movies, the ring was actually shown to be symbolic of Sauron swiping hundreds of people at a time and killing them. I mean, really, in the end the whole story was about how Hobbits were stout and strong enough to topple a Dark Lord--so the whole point of strength not being all based in "the sword" was about as subtle as a sledge hammer. The only thing he failed to do was say the pen what mightier than the sword.
I think, overall, a lot of this stems from just the translation to screen being a little crude in how to display power in a way that's visually stimulating and doesn't have the help of narration/inner monologues to help explain it.
Edit: And I know Tolkien denied it, but the symbolism for WW2 is pretty thick. I think in a lot of ways, the fact that such a diminished "little" man, who wasn't particularly bright, like Hitler, could wield so much power just through his ability to orate, was a big part of the story. Showing how power can be extremely subjective based on context was something he tried to do a lot.
