Arguably a more maintainable technique would be to use multiple classes and define, e.g. a "brand" class just for this color, so you can have a simpler standalone rule:

    .brand {
      color: #bada55;
    }

See OOCSS for more details.

While that's good practice, it's a challenge to get it right on a large legacy systems, so I still find variables useful in practice. Also, it's nice to be able to perform functions involving variables, e.g.

    .brand {
      color: lighten($link-color, 20%);
      background: ($link-bg + $page-bg)/2;
    }