Movies are all "eye-candy", with much more motion on-screen for today's ADD generation, and most of them have a stupid or non-existent plot.
When gorgeous on-screen eye candy isn't technologically possible, you're forced to tell a good story. Well, today people can be lazy, because you can generate all kinds of things with computers to make people go "wow" so you don't have to appeal to their higher nature anymore.
Also, people don't read anymore. In the 50's, 60's, or 70's, people still did a lot of reading. But as time went on, Hollywood decided to stop competing with books as far as "substance" or "content", and just did their own thing.
This has happened to other industries lately as well, such as video games.
There was a time when games involved lots of imagination and thought, and were generally "fun". Now, everything is eye candy and multiplayer.
I've seen several remakes of old movies, and the new ones ALWAYS have the same flavor that's hard to explain. I never like the remake, of course. But there are certain patterns there that a smart person could draw out and enumerate, if he wanted to.
Older movies made you think. Newer ones almost never do.