Those interfaces are not likely designed by interface designers — they’re either assembled by developers using framework libraries trying mimic things that ‘look designed,’ or “designed” by visual designers that have no more business designing interfaces than Wordpress plugin developers have designing your network architecture. Your first clue is your citing the ‘mobile first’ design— The first step in any serious interface design is researching who your users are, what they need, in what environment, and with what tools. Something being mobile-first is an implementation detail that has nothing to do with the core design. You don’t notice well-designed interfaces because if it’s properly designed, you concentrate on solving your problem and not the tool that’s solving it. If you’ve got primarily technical users and you’re not giving them technical tools, or you have a lot of power users and aren’t giving them power user tools, you probably didn’t do the thing that every subsequent decision in the design process should be based on: research the who, what, where, why, and when of the interface.
The problems you cite aren’t caused by bad design, but a lack of design, altogether.