They don't fix the problem. Nowhere on earth is there a sustainable electrical grid that doesn't pollute the atmosphere, let alone one that supports electric cars for every household. Not only that but electric cars create local pollution in the form of particular matter from brakes and tyres and they are worse than internal combustion engine cars in that regard.
Regenerative braking does not replace traditional brakes. In particular it is only really efficient at high speeds and doesn't do much in cities. EVs have no tailpipe emissions, but particulate emissions from the tailpipe of modern ICEs is very low anyway. But EVs do produce significantly more emissions from the tyres and brakes compared with ICE vehicles because they are heavier.
It doesn't have to be 100% regenerative and an electric motor in generator mode it's very efficient at braking even at high speeds. One just needs to redirect the excess energy that cannot be absorbed by the battery to a controlled resistive load and trigger both mechanisms if the brake pedal is pushed more than 30% in which case you definitely need regular brakes. Trains already use these mechanisms.
The figures in the linked article are overblown: 5,8 g/km means one throws away a pair of used tires every 1000 km, which is not the case since the average tire lifecycle is 20k to 30k km.
Incorrect. I drive a lot in the city and I use the friction brakes so little that they start malfunctioning after a week or so if I don't do some hard stops once a week or so to clean up the pad surface. I only use the 'regular' brakes if I am stopping from high speed, quickly, or at the bottom of a steep hill. Probably use regenerative breaking for >90% of all normal stops.