Ferdinand eventually confirmed his international retirement this month.
He said: "I can never understand why players don't want to play for their country. It's hard to take in.
"That is my personal view. They have their own reasons why they won't turn up, and say they are injured or whatever.
"It's very simple, I want to play for my country more than anything."
Keane reckons England will miss Ferdinand in tonight's friendly at Wembley.
He said: "Rio is so well respected, he's one of the best in the world and made his choice.
"Maybe he went about it the wrong way or the manager did, I'm not really sure about the politics behind it.
"But England will be missing one of the best players in the world."