Wenger stepped down from job as Gunners manager in 2018, with a year still to run on his contract, after more than 21 years in the role. He had won three Premier League titles and seven FA Cups, but the final years of his tenure were marred with fan protests and declining results.
The Frenchman has since gone on to be appointed FIFA's Chief of Global Football Development, the first role of its kind, and Dein feels his former club will only continue to miss out on Wenger's insight.
"He was a miracle worker, and they just let him go," Dein told the Mail. "He left in a similar way to me. I thought the club owed Arsene a duty of care, at least a discussion. We need a change but how do you want this to be done? Do you want to be involved? What can we do? Would you like a different role, would you prefer to exit elegantly? You must have dialogue. It didn’t happen in my case, didn’t happen in his. And that really hurt him. I would have done it differently.
"Look, you don’t find a brain like his every day of the week. He’s an Arsenal man, 22 years at the club. Wasn’t his knowledge worth cultivating? Look at where he is now? So he’s not good enough for Arsenal, but he is good enough to be head of global development for FIFA, in charge of 211 countries.
"He should have been used by us surely, his knowledge, his skill, his encyclopaedic awareness of players. He’s got to be used."
Dein also saw his long association with the club his loves end prematurely, being sacked from his place on the board in 2007 after helping guide the club to 18 trophies. The former vice-chairman has since been back to the Emirates Stadium but does not expect Wenger to follow suit anytime soon.
He said: "The longer I’d stayed away, the harder it would have been to come back. So sooner rather than later was better. Maybe if I hadn’t gone then I wouldn’t have gone, like Arsene. He’s hurt, he’s still bruised.
"The day I returned, I saw Robin van Persie. 'Mr Dein — what happened to you?' I’d signed him. He was one of my sons. But then, I’d just vanished. I told him it was a long story."
Dein was the man to first introduce Stan Kroenke to Arsenal, and he is open with his criticism of the man who would 10 years later end up owning the club.
He continued: "Who knows if they’d be in a better place with me there? But the direction they took — there were mistakes after Arsene left. Managerial appointments, the transfer market. And there is a disconnect now. There are two types of owners. For some, like me, the money follows the heart."
"I was a fan on the board," he added. "I could never have agreed to a project like the Super League. If I was there when that happened, I’d have resigned. They didn’t read the tea leaves. A closed shop? Nobody has a divine right. Some of these owners think they’re too big for the rest of the league. They’re deluded."