Yeah, among the things that appeared to have influenced by WebToon, this is another big annoyance of mine. I clearly took the yellow/gray's, and the difference they made, for granted. It gets a bit tiring to look through the comic sections and user profile after a few minutes. And when I use the Dashboard, I feel like I'm taking an eye exam!
And there was no reason to removal most of the color, as it's not like the website's colors went from grey & yellow to white & yellow, as you can see the grey bars when reading comics, and on their mascot. With the yellow, you can the bottom bar still (seemingly left untouched) on the home page, and they use it with the selector for sorting options.
Sigh...I know it seemed like small amounts of color, but to me at least (and clearly quite a few more people), it seemed to make a huge difference. Seemingly another change just to match the competition. I'd like to be wrong, and have it be part of a better plan (dark mode, switchable colors) but...I'm keeping my expectations subdued.
Also, for your point on bringing the old design back...I don't think it's happening. It's been asked by many, including me, but the response I got from Michael was something along the lines of "We currently cannot comment on that". So given how the redesign was rolled out without warning or feedback (and seemingly no bug testing either), the inability to provide an answer, and them seemingly pouring through the CVS receipt worth of complaints...I think they're just going to push on with this.
I'd personally speculate that something is forcing their hand behind the scene to push this update out (perhaps to copy and beat the competition). But even if that weren't the case...don't get your hopes up about a rollback. Not even about a option to switch between the designs (like Reddit). At this point, I just don't see it happening.