The title explain it all.If Madara love his brother so much ,he should have revive izuna also.I know some of you guys will say that there was no trace of izuna dna to revive him but Madara rinnegan which his a fusion of izuna eyes and his own into one.This mean izuna dna is still inside the rinnegan.Obito had one eyes,therefore he could have allow white zetsu to present the rinnegan eye infront of Obito inorder to revive izuna