I do like a lot of the darkened looks of the late '90s on their own, I just think that when so many teams did it, it really sucked some visual life out of the league. You had the Isles and Oilers going to navy blue, the Flyers ditching their signature orange in favor of the black uniforms, the Sharks started wearing their black alternates a lot more often at the expense of the teal unis, the Stars went from kelly green to a dark hunter green that was barely distinguishable from the black on their unis. Florida promoted their navy alternates to full -time road (then home) status instead of the bright red set, and the Flames were wearing that black uniform with the flaming horse head logo instead of red.
Really, I don't think any of those looks were bad on their own, but when they all replaced brighter, and in some cases, iconic looks, it kind of made the league a little dreary looking for a while.