Blogger have now reintroduced lightbox to all blogs. While they claim to have fixed a lot of the bugs/issues that were reported before, they have still turned lightbox on by default. Fortunately we don't need to apply a hacky workaround this time.
If you don't want to use lightbox then you can turn it off for each blog you write through your dashboard. Simply select “No” next to Lightbox in the Settings > Posts and Comments section (new interface) or the Settings > Formatting section (old interface). I still think this feature should be opt-in rather than opt-out but at least they are allowing us to opt-out, so I guess we should be grateful.