OTOH, if smallpox immunization isn't recommended for (about halfway down the page) (http://aappolicy.aappublications.org/cgi/content/full/pediatrics;110/4/841) "people with eczema or other exfoliative skin disorders, for pregnant women, or for people with immunodeficiencies", and they cite an article saying roughly 15% of the population suffers from eczema (and that said people may be susceptible to eczema vaccinatum complications even if their skin disorder is in remission), and since there isn't enough vaccine to treat everyone, and I imagine there would be difficulty treating everyone who had adverse reactions, and since post-exposure vaccination can develop your immunity before the incubation period is up, and since there are nastier and more effective diseases that can be used anyway, I can see the arguments for not immunizing everybody against smallpox.

(...I just realized you and I know at *least* three people who are on the "immunization not recommended" list.)