I have a theory about that particular style of light fixture. It's a PITA to replace the bulbs or clean, and with a high chance of dropping the globe (i.e., glass). Yet, this style is the cheapest out there, and thus is the one that a home builder would put in. I think the lamp manufacturers made this difficult on purpose so as to entice folks to upgrade once the the globe inevitably gets dropped. That said, there are a lot of folks selling such globes since they figure out all this and want to get something else.