I don't think it's unpopular at all anymore but Kaido was right : Oden was truly a foolish lord to bow to him and Orochi so easely and to believe that they would leave Wano in five years.
Making Oden stay alive would have signified making Zoro have a second master after Mihawk or perhaps even the only master under the right plot.
An unpopular opinion might be this one I just claimed.