Opposite to Antergos Manjaro is a) using solely their own repos, not also Arch's and b) come bloated (far too many applications installed by default) and themed out of the box.
Rather Electrolysis. Switched it on when it was not default yet, and happy with it. That killed the performance plus for Chrome (Chromium at least), but either way I was never satisfied enough with Chromium.
And there might have well reason to change the small things only, but nothing fundamentel. People hate change. If they start to turn the website upside down, their customers would start to whine, and cry, and complain. A lot of wasted time they could spend with buying stuff.
So, it ugly and bad as hell, but everybody is trained and accustomed to it. Why risking confusing customers without need?
Deceptive tactics.