Having such a robust community behind Firefox is a double edged sword. Numerous people pour their efforts into excellent plug-ins and scripts to enhance interaction and productivity, but their innovations continuously change the browser’s purpose. The design starts to become obstructive. Cutting the fat and managing space become more and more essential. I think Chrome accomplished that exceedingly well.
If browsers really will become the GUI of choice for applications, you will start seeing them treated more and more like a desktop with similar real estate expanding features.