The goal of web standards is to make things a little bit cleaner, a little bit easier, a little more interoperable and a little more predictable for web folk like yourself. In a world of web standards browsers and developers are on the same page and everyone knows what to expect. Imagine only having to manipulate one file and have the content of your website appear the way you expect on all modern browsers. That is what is coming with the focus on Web Standards like XHTML, CSS and DOM. Through the separation of content, behaviour and style, things are looking forward.
Well, XHTML is set to replace HTML. XHTML is a stricter, but that doesn't mean it's harder. However, there are some rules you'll need to follow in order to produce valid XHTML documents (ie: well-formed XML).
What else can I say? This is where prenstation is at. Style it once, and save time, money and space. Make your sites accessible to persons with disabilities, text browsers, cell phones, google and the future devices and programs with a few simple rules. Your styles are set across your site and allow redesigns to happen easily and without pain. Do it, you'll thank me later.