Earlier quoted context omitted.
Why does it seem like everyone is moving to those curved tabs? They've always seemed like a waste of space and the overlapping bits make for an inconsistent tab UI.
I'm not sure what you mean by inconsistent, but I imagine the point is to give a slight depth -- better highlight the foreground tab.
Open 4 tabs. click tab 1 and then tab 3. What order do you display the tabs in? Does tab 1 overlay tab 2? If closing tabs don't to the last open tab this now means that the visual stack is not accurate to how the program operates.
I understand the depth but there are better ways to show it that don't take up as much space nor have to deal with issues like visually showing the tab's z-order