Former Wigan rugby league star Edwards has been linked with a role in the England set-up but could yet work as an assistant to new Wales coach Warren Gatland, and insists the RFU could not have justified dispensing with Ashton.
"There would have been no justice in the world if they had lost their jobs after getting to the World Cup final," Edwards told the Daily Telegraph.
"I would have been upset if I'd lost my job after taking a team to the World Cup final."
Bristol director of rugby Richard Hill felt the decision to retain Ashton was the right one for continuity in the national team set-up.
"They did an amazing job in view of the short period of time they had with the team. It might be sensible to give them a short contract because then there can be changes, if necessary, two years or so out of the World Cup."
Ashton and his team came in for criticism after the tournament in France from Lawrence Dallaglio and Mike Catt, but England and Bath prop Matt Stevens claimed there was support among the players for the coach to continue.
He added: "The majority of the squad have stuck with Brian and for the good reason by the end of the World Cup we were a pretty solid unit. It's important that we continue to show that solidarity."