The problem is, that with every new development comes new risks. We could go back to living in caves and bashing animals with clubs, and cooking them over fire we set with a bunch of rocks and wood. That would be a lot safer than cycling to work each day, with nuclear missiles looming over our heads, not to mention the countless other risks one takes just by stepping outside of the door.

It's the same with the web. You could take away the scripting, but you'd end up with technology that would be as useless for today's man as a hunt & gather culture of a caveman would be. We've grown to depend on it, just like we depend on cars (that pollute the air, and are the cause of many a deaths - more than client-side code execution, I'd think) and nuclear power.

With technology, comes a risk, and I don't think there's a way around it.