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That's because they hadn't used it yet. :) In all seriousness, everyone was in on Java. Even Microsoft (Everyone was in on Java, even Microsoft ( https://en.wikipedia.org/wiki/Visual_J%2B%2B ). So most of us saw browser plugins and applets as the future, and some of those plug-ins were very impressive in those days. JavaScript was seen as a glue language to manipulate components built in better languages. We thought…
I also thought Java was the future. But, Java tried to be an entire virtual OS, and gained too many security holes because of that. Flash had a similar fate. It's not that JavaScript solved that, it's that it's built into the browser such that you can't really skip it. Like the Java and Flash engine, a web browser is also a fat bloated leaky client. However, if you toss the first two, you are then dealing with 1 fat…
I suspect performance and inconsistent experience killed Java applets and Sun stopped caring about desktop Java when they realized they can't make much money off it. Flash stuck around a lot longer than Java because it was fast, fun and ran consistently. It still lingered for some time after Jobs poisoned it.
Honestly, I don't think people cared that much about running updates. For most people, if the computer tells them they need to update, they update. I also don't think average users cared about security issues back then.