So for sites or apps where loading speed has a direct impact on your bottom line and that don't really benefit from real-time features (such as an e-commerce site) I don't think Meteor is a good match, at least for now.
I also don't think Meteor is needed for purely static content sites. For example, for our own book site we're using Jekyll.
(And yes, I know speed is important for every type of site. But in most cases, I feel there's enough other benefits to building Meteor apps that you can ignore this downside for now).