“Web design programs are the Japanese infantrymen left behind on the Pacific Islands at the end of World War II.”
Because WYSIWYG programs (DreamWeaver, FrontPage, etc) will only ever be able to create the version of HTML they were programmed to code. Web design programs can be compared to the Japanese infantrymen left behind on the Pacific Islands long after World War II had ended – the ones who still believed that the war was ongoing because no-one had ever told them otherwise. DreamWeaver 4 will only ever be able to create the version of HTML that was current during its year of release, at least as far as its visual design tools are used.
Knowing only the graphic design end of a program – be it a DreamWeaver or FrontPage – can be compared to only knowing how to drive an automatic car. If something goes wrong with the car, you are forced to take it to a mechanic. In web design, you are the mechanic.
Web design programs can introduce bugs into your code, or be incapable of coding a feature you need. Knowing HTML allows you to “get under the hood” of any web design program.
Web programs also tend to introduce more code than is needed for your page. (Microsoft programs, in particular, are notorious for this, but they are not alone). By “rolling your own” code you have a greater chance of creating leaner and lighter code, often 10 - 15% less in size than the equivalent WSIWYG-created page. This translates directly to decreased download times and reduced site overhead costs for bandwidth and storage.
Coding sites with standards compliance allows you to “future-proof” your work.