I see the point you're making, but what exactly is 'excessive'? Surely it changes over time? In the 1930s, 50mph was fast, 70+ was probably a frightening thought. The actual value of 'excessive' should increase year by year as cars add more and better safety features. Just look at stopping distances (real ones, not theoretical) - surely they must have decreased drastically since the 1950s, what with radial tyres, power assisted braking, abs etc etc. So the dangers posed in a 30mph environment then possibly equate to a 40mph now.
To answer your actual question, I don't think the gadgets make that much difference to how safe we feel when driving (and hence how fast we drive). For myself, it's much more the basic handling of the car, how it responds. I won't go as fast in the wife's car as mine as it just feels more unsafe (Freelander vs Fiesta).