The visitors dominated for most of the 90 minutes to claim their first league win of the season thanks to goals from Peter Hartley, Liam Donnelly and Chris Long.
Hamilton, who scored a first-half penalty through Ross Cunningham, had Jamie Hamilton sent off after just 20 minutes allowing Motherwell to coast to the win.
Robinson said: "No game is ever easy. But what we did do is dominate the whole game. When they went to 10 men we took our foot off the gas a bit but our decision-making was very good.
"At 3-1 we managed the game well. We're a young side and that was the pleasing aspect. It should have been more goals if we'd been more ruthless."
Robinson felt players like Long, Sherwin Seedorf and Jermaine Hylton would truly flourish once they started to believe in themselves more.
The manager added: "That's two in two for Longy. He's a very good footballer. If we can get him believing and Sherwin believing and Jermaine believing then we'll have three very good players.
"We weren't the worst team in the world after being beaten by Hearts last week and we're by no means the best team in the world after beating Accies. But it was a very good performance."
Hamilton boss Brian Rice felt sorry for teenager Hamilton following his early dismissal but had no complaints about the decision or the result.
He said: "We were up against early on having the man sent off after 20 minutes. And the double whammy was they got a penalty kick as well. But I'm not here to make excuses or blame referees.
"The referee calls it as he sees it and you get on with it. There are no excuses. It was 11 versus 10 but Motherwell were the better side and they won the match.
"Jamie will be fine. I've not seen it back. It's a handball so the ref has called it. Andrew Dallas is a very good ref. I have a lot of time for him and I thought he refereed the game well so I've no qualms about that.
"I'm old fashioned I like talking about honest mistakes, individual errors, human nature. We all make mistakes. We're not going to lambaste them for that. It's a difficult enough job."