Trust me, great websites (that are effective) have much less to do with validation errors (or lack their of) than usability, color, style, feelings, and all that other good stuff.
and unfortunately he is absolutely right in the short term. but the web is not a short term medium. with innovation and change coming along at such a rapid pace, any good design has to not only work now, but remain accessible for at least the next twenty browser upgrades (in the same number of browsers). it just isn’t possible for you to update your site that often. and yes, with the IE juggernaut still on the loose, we also have a lot to think about for backwards-compatability - but that’s an additional concern not an alternative one. we can’t ignore the future because the present isn’t perfect. it’s time to start desiging sites (and browsers) that follow the standards - and have “all that other good stuff” - because what we do on the web now determines where the web can go from here.
it’s a different game, but once you understand the rules the limitations become a challenge and you start playing with all the other possibilities. you can’t do it the way you always did, simply laying out static text on a page. your text is going to move around on you, out of your control. what you can do is give it advice. your immediate instinct is to hold everything in place, position everything absolutely or use tables, no-wrap tags, pixel widths, anything to keep that text right where you put it. you can try that all you want, but it’ll just break it when i visit your site with my differently-abled browser, and if your content is all mangled by semantically-incorrect jargon, i’m going to get frustrated and go somewhere else. then i’m going to write nasty posts about you on my blog, and be forced to apologize about it later. neither of us will be happy. the world will be a worse place for us all to live.
start thinking differently. it’s not about whether it breaks but how it breaks. what you’re designing is dynamic. incorporate movement. make it interactive. make it fun to play with. you can also design multiple looks for the same content - but it will be a lot easier to do if you code by the rules. the W3 is your friend and the semantic web will make your life a whole lot more exciting if you learn to play with it. learn to cheat without ever breaking the rules. the web’s a playground. it’s a sandbox. don’t conquer it, play with it. user-friendly requires a personality and a sense of humor - not just a negative ‘realistic’ outlook on the state of browser support. first be forwards-compatible, then worry about being backwards-compatible.
then go kiss your lover and get a good night’s sleep.