England controversially axed their all-time leading run-scorer across all formats following a 5-0 series loss Down Under where he was their highest-scoring contributor with the bat.
"You were looking for some heads to roll and, for some reason, Kevin Pietersen's head was in the way," Richards told BBC Radio Five.
"He'll have been disappointed with the series in Australia, but overall I think he's been a good servant to English cricket," added Richards, one of the greatest batsman in the history of cricket.
Richards' comments echoed those of retired all-rounder Andrew Flintoff, a former England team-mate of Pietersen's, who was at a loss to explain the 33-year-old South Africa-born batsman's banishment from international cricket.
"If his attitude was that bad, why did he play five Tests (against Australia)?" Flintoff said in the Daily Mail.