Earlier quoted context omitted.
Originally, it was not known that HTML pages would be so finely designed. It is not a naieve dichotomy, it is an attainable ideal that has had a very positive effect on the state of the web. We owe huge thanks to this movement that lead both to the demise of proprietary browser extensions (like flash) and to the awesome technologies in browsers today such as these CSS features, new HTML elements and transport protoco…
These things, while beneficial, don't owe their existence to CSS. Instead, introducing eg. CSS shapes or `content: ` (as two extreme examples) was the way of least resistance/guerilla tactics, as opposed to putting the functionality into SVG proper, or aligning the layout box model better with the DOM model, resp. Now what we're left with is a way overcomplicated mess for generations to clean up. There's a reason Moz…
What I am talking about is CSS Zen Garden and the movement around it of frontend web developers professionalizing, rejecting table layouts and non-standard browser features.
This was enabled by CSS being barely powerful enough, and people creative enough to make it work. Eventually the movement won, non-IE browsers won market share and the way was paved for a more healthy evolutionary path of the web which has yielded these new features.
You look at CSS from a perspective that it's hard, as if there exists a solution somewhere that is easier. Before CSS there were simply the less powerful HTML features, the 'easier' but less semantic and non-adaptive tools like Flash or SVG, and the always present and expertise requiring method of simply imperatively coding the styling in WinForms or whatever.
CSS was absolutely crucial.