Most of the information you find on the internet are in the written form, and even after the popularity of the visual content (videos, images), textual content has its own significance. I am sure it will never lose its importance regardless of how technology will advance in the future.
According to ia.net, 95% of the total information on the internet is in the text form. Therefore, web designers must know the art to arranging and styling the written content to make them more readable and appealing. These include selecting font family, font size, font colour, line spacing, letter spacing etc. Technically this art of styling and arranging the written text is called Typography.