Whilst understanding your specific complaint, I must counter that many (if not a majority) of users find the updated multitasking user interface to be both flexible and productive. For those that have difficulty, a resistance to learning about the new UI controls and features is perhaps a more accurate truth.
Your complaint concerning accidental triggering of the multitasking controls, by tapping the Safari address bar, can be simply explained…
Yes, unless you are extremely accurate in tapping only the address bar itself, a central tap can trigger the multitasking function. You have sub-consciously “learned” to tap the centre of the bar - because you have been conditioned to tapping the actual visible text to edit this input field. As this text is centre-justified, you are unwittingly attracted to the centre - where the touch zone for the multitasking button is located.
Now the [mental] fix that should resolve most of your issues - but accepting that you need to “reprogram” what might be several years of conditioned behaviour…
In Safari, the entire URL field is a “hot zone”. Just tap anywhere in the visible field (not just the visible text). Armed with this knowledge - and admittedly a little deliberate and conscious practice - you will quickly become accustomed to a slightly different way of using Safari. A new “habit” will emerge - and become your new sub-conscious behaviour.
