The Italian spent a single season at the King Power Stadium club, leading them to promotion to the Premier League.
However, he left this summer for Chelsea, with Simpson understanding Maresca’s reasons for leaving.
"It’s a bit mad to be honest, I was surprised he (Maresca) left," he told SportsBoom.com.
"I just don’t know why you’d want to leave such a great club. He’s got them promoted as champions and he’s got everything there to be successful.
"No disrespect to Chelsea, but look at the foundations at Leicester, the training ground and the facilities. But we all know what it’s like whether you’re a player or a manager, a bigger club comes calling and you get tempted.
"However, saying that, Kieran McKenna decided to stay at Ipswich when Manchester United were meant to be interested him in.
"As a player that must be great for them, he’s showing that commitment to them. They’ll be on holiday now and it will great to have heard the manager has signed a new contract.
"But at the end of the day we just don’t know the ins-and-outs do we?”