Memory Charm

By using memory charm, you may alter/erase whole or part of someone's memory. I see this as the violation of a person's individuality as this deprives of their original thoughts. We also have the instance of Gilderoy Lockhart who used memory charms in such an undue manner. Then how come memory charms not illegal or Ministry of Magic not tracing out when and where one has used it?

Wanda Maximoff and Hermione Granger has a lot in common

First, Hermione is considered the smartest witch of her age, and Wanda's powers were altered with the Mind stone.

Second only Wanda had the power to destroy the Mind stone. Likewise Hermione is the only one in the Golden Trio who did research and knew all the ways to destroy a horcrux. Also they had to alter people's minds. Hermione had to wipe her parents memories to protect them. Wanda has used her mind abilities to alter their memories.

Anyone able to find more similarities in these two iconic witches?

Were Hermione's parents confused when they saw the empty frames? (Hermione's old muggle school pictures)

A few days ago I was thinking about KotLC and HP, and I thought of this question. I know in Keeper of the Lost Cities (another book series) memories can be triggered after they are removed. So, I was wondering if, after using Obliviate on someone, said person's memories could be gained/activated again? I read the page for the Memory Charm (Obliviate), but it didn't mention memories being triggered again, except through torture, but I mean other than that.

For example, say Lockhart removed a woman's memory to claim her achievements for himself. And say he wrote a book about those achievements. If that woman were to come across that specific book, and read it, would it feel familiar to her/would she remember what happened?

Or

If Hermione's parents (whose memories have been erased/altered) came across a picture of her somewhere, somehow (maybe on a Newspaper), would they recognize and remember her?

This has been on my mind for awhile. Shouldn't Memory Charms be classified as an Unforgivable. I mean, the Imperius Curse controls a person and takes away their free will, but erasing and/or altering a person's memory seems just as bad, if not even worse, don't you think?