Too Many People Want a Piece of Firefox These Days

Boing Boing Gadgets links to a Washingpost blog which complains about Microsoft quietly installing a Firefox extension without permission. This isn't the first time that this has happened. While I like AVG Antivirus, they have been installing their own Firefox extension for quite some time. As with Microsoft, they do this without permission, probably on the idea that they are doing it for the user's own good. But this is a troubling trend. One of the reasons that I use Firefox in the first place—indeed the reason most people probably use Firefox—is because of the degree of customizability and control that is allows. When companies decide that they can install extensions on their users computers willy-nilly, that is a bad thing. They are essentially telling their users, "We know better what's good for you." It erodes trust and quite frankly I'm not even sure that it is legal. Firefox afterall is made by an independent company, they are not owned by Microsoft or by AVG Technologies. So my question is, aren't these companies acting like virus writers when they do this and potentially opening themselves up to a lawsuit? If so, it would probably serve them right.