If I wasn't a grumpy old product manager, I would be tempted to get cynical and say that flat imposed higher cognitive load which keeps you on the page/UI longe

If I wasn't a grumpy old product manager, I would be tempted to get cynical and say that flat imposed higher cognitive load which keeps you on the page/UI longer which gives more time for other things to get your attention and create the mental lock in thru mix of attraction and sunk (time) cost...i.e.ive spent so long to figure this out I may as well stay and look around. Another Responder pointed out that material design is better. Maybe I'm ignorant but I don't see how. Perhaps icon quality/diversity is better these days but the basic premise of 2D facsimile for real world 3D objects is still there. Personally I prefer that UI things can be easily and uniquely related to action. This can be achieved by education I. E. sliders now look like nice rounded corner progress bars of yesteryear but we have gotten used to them thru their imposition on us by G and A. That said I have used a few very old GUI programs and their look now is jarringly uncomfortable even though the tools are great and the UI is clear. Progress?