I don't think films are quite as violent or edgy on the whole as they used to be. I can't think of a recent movie that was as edgy as Taxi Driver or American History X or the like.

I can only assume you're talking about actually good movies, there's plenty pretty terrible movies that does push the boundary of extreme violence and disgusting shit (Human centipede, a Serbian film, the entire torture porn genre etc.) Taxi Driver and American History X are of course, unlike previously mentioned, actual movies with actual plot and dialogue and characters that actually want to tell a story.

However I still disagree completly.

Sure Hollywood blockbusters are pretty safe when it comes to the violence, but they've always been, if we're talking about violent thrillers, there's not really an argument that they're way more violent today, one only have to look at your examples. American History X pans away from the violence, there's only really implications of the actually gruesome stuff. Sure the violence still carries "oomph", but that's an illusion, a filmmaking trick that's still used today. I wouldn't put much difference between the curbstomping and the pencil scene from the Dark Knight to be honest, they're fairly similar in their implication to gruesome head injuries and death.

Taxi Driver also features people getting shot, sure they get all bloody and messy, but would you really say that doesn't happen anymore?

This might be a gap of the type of films you and I watch, because if you hoenstly consider The terminator to be "really violent dark and edgy", it really does bring the impression you haven't done any effort to look for those types of modern films, because they are oh so much worse. I saw the terminator when I was eight years old man, it really isn't that terrifying.