I credit Solarized with setting the baseline allowing proper "dark" themes to be more commonplace. I'm going out on a limb, but perhaps macOS' Dark Mode, or VSCode's dark mode, wouldn't exist without Solarized blazing that path.
It's kinda funny how, before Solarized, I would see tons of gimmicky themes like some that were going for a Matrix or "classic terminal" feel, going all in on a certain theme but eschewing real usefulness. I want my basic terminal colors to remain adjacent to their intended hues! I want different keywords/tokens in my code to be distinguishable!
Ethan's application of color theory/science to the landscape was like a beacon in the darkness.
Before Solarized, I used Zenburn (I actually still do in some environments, I'm not too keen on the blueish hue of Solarized backround.) I also like Tango Light/Dark.