At first I thought prototype OO was incredibly neat and useful, but am now leaning more towards the former than the latter.

I’m judging usefulness by, well, use.

Prototype, one of the most commonly used libraries, extends prototypes, yet it also provides provides “Extend”. Prototypes enable mixins and are thus a great building block, but it seems that isn’t what we want for the 80% case.
What about Macromedia? They have probably written the most ECMAScript out of anybody.. yet behind the scenes, prototypes aren’t being used. When the codebase was small, it was there, but usage has been entirely phased out.

We have enough power to hack along, but it seems fairly clear that we like crutches and guarentees, and don’t feel like constantly reinventing the wheel. I’m interested in soft types or something along those lines that is all the rage these days.. I don’t think Strict mode is the solution.