I don't think nervousness about a particular implementation approach is a reason not to implement WebGL, just a reason not to do it in what I gather is Chrome's way.

On the other hand, Chrome's strategy might just be getting explained poorly. My nervousness comes partly because the way it's described sounds like a filtering strategy. If it's more like a whitelisting strategy, it could be considerably less scary, and more in line with what I was kind of expecting from browser vendors.