It is not only for the 21st century gear-heads rather is something that is meant for everyone. It helps you to fine tune your web design software for speed and efficiency. Often the web design packages available in the market generate code which does not work smoothly in all browsers.
For example, the stuff that may be fine for Firefox could be broken when used on Internet Explorer or Opera. In order to debug a faulty page generated by the web design packages you should have a fair understanding of this important tool.
HTML work wonders when it comes to portability and code properness
One can write HTML code in any types of text editor but in WYSIWYG editor you can only build a website if you have the WYSIWYG editor installed in that computer. So in case of travelling from one place to another there is the problem of portability.
If you do not know HTML you have to depend on the on getting the editor installed in that very computer you are using for building, updating (no matter how small or big the update it) or modifying a web page.
HTML is the need of the hour
A resume studded with it makes a good impression on the employer. It helps you to raise your intellectual coefficient and expand your mind. In stark contrast to the editor which has a limited number of functions with HTML you may create your own functions and codes which are customizable so they feel and look exactly as you want them to do. One of the reasons why people in ever increasing numbers are learning HTML nowadays is that it is the doorway to endless possibilities.