NFL D-Coordinators did a terrible job of preparing for the read-option looks and Alfred Morris was far better than anybody could have expected.
The problems I saw with RG3 right away is he had difficulty seeing over his linemen. But, he could counter that in his rookie season with play fakes. The LB's would bite so hard on the play fakes the receiver would be wide open over the middle. That's typically a tough throw to make unless you're a 6'4"+ QB with an overhand throwing motion. But opposing defenses at that time were making it easy by biting on the play fake so much that virtually anybody could make that throw.
The 2nd time the Cowboys faced the Skins, you could see that Rob Ryan had instructed the LB's to not bite on the fake. And it worked as far as stopping the pass goes. The issue was that we had so many injuries that we had guys on the field that had no business being there and Alfred Morris ran for a gazillion yards (200 yards to be exact).
By 2013, defenses were completely focused on stopping the read-option due to the success of RG3, Kaepernick and Wilson. They started to blitz it more often. I remember Kyle Shanahan raving about the read option because he saw defenses stopped blitzing it. I knew that Shanahan was in real trouble if he thought it was going to stay that way because the best defense against play action is to blitz (play fakes take extra time and can't handle guys getting upfield).
Eventually, that led to the Skins trying to dump the read option and go with a more traditional West Coast Offense.
The issue I find with WCO is that the coaches tend to:
1. prefer footwork and making the checkdowns at the correct time over QB's with better and more accurate arms and that move the ball downfield.
2. tend to think that athletic QB's with poor footwork will fit in their system (same happened to Mike Vick in Atlanta)
That's why I could see the Skins coaches being more apt to like Cousins than RG3. Doesn't mean that Cousins is a good QB though.
The good thing about an offense like Garrett's is that it's not nearly as footwork oriented as the WCO which is extremely timing dependent and if you don't nail the footwork down, it throws the entire play off.
RG3 sorta reminds me of another former Heismann winner that had a rocket arm and good athleticism and went to a dysfunctional franchise and floundered before going to one of the top teams in the league that was from his hometown and was given time on the bench to develop and learn. He went on to win 2 Super Bowls.
YR