A brace from Simpson, on his first start for the club, and a third from Mexican starlet Carlos Vela put the young Gunners into the fifth round at the expense of a near full-strength Wigan.
"Seeing the players with experience in the tunnel is a real boost for all of us. I spoke to Ade (Adebayor) before the game and he just said 'hit the target'," Smith told Sky Sports.
"We knew Wigan would give us a hard time and we had a lot to prove."
After the youngsters' thrashing of Sheffield United in the last round, manager Arsene Wenger believes his rookies showed once again that they are the best crop ever produced by the Gunners' famed youth system.
"I am very proud of the players and of the quality of the display," he said.
"That's the most complete side of youngsters (Arsenal have had in his time at the club), and with many good young English players.
"It's very good for the future of the club to see that it is in safe hands."