There are scientific reasons why lightbulbs are shaped the way they are, glass strength, illumination, etc. However, due to the overwhelmingly male influence on inventions at the time, and as with many other items invented in that time period, they are phallic. Think, wall outlets with their male/female configuration, the battery, the stapler, etc.
If I could go back in time, I'd influence the creation of the lightbulb such that the accepted standard would be heart-shaped. Illumination and glass strength would not be compromised, as far as I can tell, but we would eliminate the phallic shape. Wouldn't that be a nice change?