A good tool like SASS/Less is not something to sneeze at without researching fully.
I also think the mixins and nesting are overstated in terms of increasing the efficiency of designing sites with CSS. I am not typically declaring colors 20 times, or doing nesting so deep that it becomes confusing.
The benefits don't outweigh downsides of dealing with SASS files and preprocessors.
Everybody. We no longer FTP the CSS into the production server like it's 1998. We also minify (a pre-processing step) and concatenate (a pre-processing step). LESS/SASS is just another preprocessing step.
>Some times it's ok to have to declare #fff more than once...
Yes, if you are working on some small / toy site. Being able to have logical names for colors and change them all at once is very valuable for anything larger.