Standards aren't important to end users, but they're critical to developers.
I'm having a hard time seeing that as an argument that Firefox changed computing. Firefox is an end-user application. Even in the darkest days of IE dominance, end users could choose from several browsers that worked decently enough. Gmail debuted in 2004, at the height of IE's dominance, so IE didn't prevent innovation and evolution in web programming, either.
Even for web developers, better compliance with standards hasn't changed things that much. Professional web designers still have to make sure everything works in IE6. They depend heavily on cross-browser libraries that hide browser incompatibilities, and they still regularly run across discrepancies, even between different highly-standards-compliant browsers. The web designers who sit near me at work test against IE6, IE7, IE8, Firefox 2, Firefox 3, and a couple versions each of Mozilla, Opera, and Safari. Plus they make special mobile versions of lots of pages, highly optimized for iPhone but also tested against BlackBerries.
And yet I still see professionally-done pages that don't render correctly in Linux Firefox. dominos.com is unusable under Linux Firefox, for example. Whether that's a bug in the page or Firefox or Flash or Firefox's embedding of Flash, it shows that web standards haven't changed the basic rule of cross-browser rendering: if the developers are committed to testing and tweaking their code against a browser, then it will work with that browser. Otherwise, it's a crapshoot.