[Dan Zollman]

It still wouldn't make sense to replace certain elements with divs or spans if you're not writing the code fully with CSS, or to change that one tag to be XHTML Strict valid when you're writing the rest of the site with HTML 4.0 Transitional. Consistency is more important.

And it's not necessarily "not as perfect as it could be". It's true it's not valid, but you should have a reason for wanting it to be valid. Otherwise, it's perfect if it's what you need it to be.

I would say that if the onclick attribute is what you really want, keep it. In general, I do agree that less attributes and more CSS is better--just don't use it if you have a strong preference for older HTML.