Some excellent answers here already, but one thing no-one has pointed out is the whole standards issue.
I know at least the GIF standard is copyrighted by Compuserve and while I'm not a lawyer I'm sure there'd be some sort of royalty fees or something involved.
While yes you could just support other graphic formats but people use gifs and jpgs most commonly.
One other not mentioned so far is lynx, yes not perl solution or a graphical browser but free and does a good job of html, but I personally only use it as a scrape by measure, because I've come to rely on graphics.
I'm sure a lot of other standards have thorny legal issues as well like Java and VBScript support, and these days you need that sort of stuff in a browser because people's sites use such technologies (as much as it pains me).