The big frontman - much maligned in the Three Lions shirt after scoring just seven goals in 62 appearances - called time on his England career after the failed World Cup bid.
He has recently been on fire for Villa and England boss Fabio Capello has tried to persuade the 32-year-old to reconsider his retirement ahead of the forthcoming Euro 2012 qualifier against Montenegro.
However, the Villa forward has stuck to his guns and Petrov believes England will come to regret his decision.
He told The Sun: "I think England will regret the day Emile retired.
"He has been a top Premier League striker for years.
"And every time he played for England he helped those around him - Wayne Rooney, Michael Owen, everyone.
"Yet people have never given him enough credit. He's very underrated.
"I know how hard he works and how important he is for our team.
"I also know how important he is for England.
"But sometimes you only appreciate someone when they are gone - and I think that will be the case with Emile."