Here is an excellent article on Developing with Web Standards.
It neatly starts with the history of internet, and starts going deep into why should anyone should develop with web standards in mind.
Some of the key advantages are :
- Simpler development and maintenance: Using more semantic and structured HTML makes it easier and quicker to understand code created by somebody else.
- Compatibility with future web browsers: When you use defined standards and valid code you future-proof your documents by reducing the risk of future web browsers not being able to understand the code you have used.
- Faster download and rendering of web pages: Less HTML results in smaller file sizes and quicker downloads. Modern web browsers render pages faster when they are in their standards mode than when they are in their backwards compatible mode.
- Better accessibility: Semantic HTML, where structure is separated from presentation, makes it easier for screen readers and alternative browsing devices to interpret the content.
- Better search engine rankings: The separation of content and presentation makes the content represent a larger part of the total file size. Combined with semantic markup this will improve search engine rankings.
- Simpler adaptation: A semantically marked up document can be easily adapted to print and alternative browsing devices, like handheld computers and cellular phones, just by linking to a different CSS file. You can also make site-wide changes to presentation by editing a single file.
Go ahead and read it..Its worth the time.