It's not perfect but this, speaking as a casual observer, is something I think will improve with time. It took far too long to move away from fixed d-pads and now more games are experimenting with on-screen zones you tap to fire. There's still a lot of unwieldyness exactly as you noted but I think this is a surmountable challenge.
I'm not sure how this could really be surmountable. With a controller you have access to at least 6 simultaneous inputs, more if you do some finger claw tricks or have back buttons or something. A keyboard and mouse gives you around the same or more simultaneous inputs. On a touchscreen you can make 2 simultaneous inputs.
Most action games require at least 3 simultaneous inputs to be played effectively.
There's definitely workarounds like the ones you mention, but unless a game is actually made for touchscreen controls, as in optimized for no more than 2 simultaneous inputs, it's not going to be as playable on a touchscreen as it would be with anything else.
Unfortunately, some genres of game just aren't as suited to only 2 simultaneous inputs.
There's lots of fun touchscreen based games, but they're always better with game mechanics specifically suited to touchscreens.
