I think that's a great feature. Loading images manually is always annoying and isn't a great user experience. Novice user's don't always understand why it's risky and they probably opt to display the images anyways.

However, one interesting question is how can third-party analytics will workaround this? Is there a way? Given that gmail holds a large market share of email users, this is really going to negatively affect the usefulness of such services.