Many are undeniably garish by today's standards, on today's devices, and although they were maybe more refreshing to our palettes at the time and less intense in the default monitor color spaces back then, I must confess, I distinctly remember vetoing several of these desktop pictures as a late 90s Mac user, including the ones you pointed out. And the era of subtler, muted colors and tones showed up pretty quickly after these for valid reasons.

I still like the UFO ones a whole lot though ^_^