The mid 90's Huskers defenses says that the "read and react" you're advocating is pretty much worthless. However, Kevin Cosgrove's defensive style completely agrees with you.
And for the record Uncle Rico....I played DT...and I only worried about a screen or draw when I saw the tell tale signs of pulling lineman or one that let me go without any real resistance. In other words, I played fast and aggressive, but I kept my head up and played with smarts.
The best defenses we ever had here at Nebraska, those from the 90's run, played fast and aggressive and didn't worry about getting beat. Because they knew that if they played mean, fast, aggressive, and full bore on every snap by the time the offense "popped" a big play the Huskers would be up by 50 and it wouldn't matter.