Those that use Firefox love how it works. They know that it does not install software without your permission, and it tends to bee more secure overall. Well that is not always so true when using Firefox on a Windows based machine anymore.
See with some recent security updates to the .Net framework, Microsoft also installs an extension into Firefox without asking, and that is not all. The extension is tough to remove (you have to go into the registry to remove it), and it allows software to be installed on a machine without a user even knowing it.
Now security updates are important, but how can we trust them from a source such as Microsoft, if they are doing the same things as phishing and adware sites? Honestly, these underhanded practices really have to stop.
You can read more about this at ZDNet.