I think the tracks were rougher, less consistent surfaces, cars were a bit more of a handful, tracks definitely less safe... It let a brave driver send it into a fast corner a bit faster than a driver who like to have his brain rattled a bit less while spotting his braking point, at 150mph with scary crash barrier waiting for him...
I wouldn't say modern F1 cars and tracks are easy, but I think they are more consistent and predictable... The guys who spin out a lot now are the bravest ones as they are overdriving beyond their talent, but they now its not life and death, or even risking injury. Also the heavy cars, and tires now don't really reward slides or air time over a curb...
Having the tracks a little less ideal, would let the drivers do things that can't be modelled on a simulator.
Supercross shows this most IMO, the factory bikes are all pretty equal, tires don't degrade during a moto, but lap times have a much bigger variance, and the riders can do single laps or even sections that are exceptional, perhaps impossible by anyone else on the track that day. Or maybe another rider could go through the whoops that fast, but isn't going to risk as much? The old F1 tracks and cars could let Senna, Gilles, Andretti, or Mansell do stuff that no one else was willing to try that day.
