The conversation, Who REALLY cares about your site validating, reminds me of the â€œWhy bother with usability?â€ ones that pop up every once in awhile.
The way I view it, is that every step we take towards presenting a user centered web site, with user centered web pages, is a step towards customer satiisfaction. Even if you’re not selling anything, you’re “selling” your worth as a site that merits a link, referral, social bookmark, visit, any bookmark, etc.
Validating code is another step in the web site development process. It goes along with learning CSS, PHP, SEO, accessible forms, and more. Sooner or later, you may find that your efforts matter to somebody.