Let's say I have the "Modern" Remote Desktop client connected to multiple Remote machines. When I click the RDP Taskbar icon, the Window Title bar appears immediately and stays there for 5 seconds. My immediate task is to hover over the top of the RDP window in order to select the Remote machine that I want to manage. I am forced to wait these 5 seconds for the Title bar to disappear.
I have also, on multiple occasions, accidentally closed the "Modern" RDP client because the Title bar's X button overlays the X button of a window in the remote machine.
It's actually real simple MS; whenever there's a controversial feature - make it optional. NEVER add a UI feature that can't be turned off. Problem solved. You've been taking way too many queues from Apple in this regard lately.