The gravel run off areas were replaced because of safety and continuing the race. They didn't want cars skipping across the gravel into the barriers, or digging in and rolling, and then having to stop the race to clear the track and dig out cars. They also wanted cars to be able to continue racing if they made a mistake and went wide, in order to keep the spectacle going. This was why all those tarmac areas were introduced in the first place.
Drivers of course have figured out how to gain advantages from this and continue to push the limits. It's the stewards inability to consistently police and punish track limit infractions that are the problem.
Almost needs a hybrid of a narrow but significant enough strip of gravel or astro then tarmac after.