Windows did have color accents, like the dark blue selection, it's just a bit muted and stale by modern standards.
It's a good idea to keep the chrome be chrome-like so color can be reserved for meaningful elements (like red for warning, green for safe, blue for selection etc.).
Notice that although end-user apps are all colorful and fancy these days, that most pro apps have remained very conservative, erring to light or dark gray and using color semantically only (think photoshop, 3dsmax, autocad etc.). This tells us something.
