Writing pure CSS is not faster than using a preprocessor like LESS or SASS. Common CSS styles that need to go into the stylesheet that need to be configurable can be simply abstracted into mixins. It is also far easier to read less or scss stylesheets due to neat nesting so you can easily see selector priority.

I generally prefer simplicity too, but for CSS at least, working with the preprocessors far trump working without for convenience, flexibility, speed of development, and scalability.