Is your point that Harry isn't shocked by Snape's behavior, so that a good many readers aren't, either? I don't remember if Harry had a general opinion about Snape's viciousness.

The women who find Snape attractive aren't children themselves-- I don't know what the typical lower age limit for liking Snape is.

IIRC, Rowling hated the way Snape taught. She could have presented his nastiness as part of a useful toughening process, but she didn't.

Of course, as the books went on, not only did he eventually redeem himself, but (earlier) Umbridge made him look like a relatively less awful teacher.