How many drivers use the full power output of the engine? I doubt very many or very often.
And it's not certain that the engine is going to knock on 87 octane, or that there would be a noticeable loss in fuel economy. Since, all else being equal, 87 octane has a higher energy content, the fuel efficiency might actually be better. (In real life this is overwhelmed by the ethanol fraction, which might go either way depending on the blend.)
>> "It will prevent it from happening AGAIN during this drive cycle if its within its parameters, it will not prevent it."
That's not how the ECU works. It detects the onset of knock while it's still below the level of perception and damage. It immediately adjusts the timing and perhaps adjusts the mixture to limit the knock, but it doesn't persistently change the settings.