Macros are also pretty easy to define \newcommand\important[1]{\textcolor{red}{#1}}
And of course it has first-class Unicode support
#let important(body) = {
text(red, body)
}
But whatever you do, #important[Dont *panic*!]
The rub comes in when you want to pull that content out to render it in a format that isn't meant to be camera-ready, like a Web page or an e-book. TeX, even with Leslie Lamport's LaTeX macros, doesn't give you an ergonomic mechanism for marshalling out the semantic structure of your document to reuse elsewhere.
You're left parsing the TeX yourself, and that sucks.