There's nothing to learn. Even if you use nothing more than nesting it's a huge boon to productivity and readability.
Maybe it was that a clear winner never arose between LESS and SASS or maybe that I always let things play out a bit before jumping onto a trendy technology. I guess I'll have to just get with it since it's not really going away.
.header {
background-color: orange;
p {
font-size: 16px;
}
}