Iblis became arrogant. That's why he disobeyed God.
There is nothing noble in either of those things and if we are arrogant and are defiantly disobedient of God, we will not make it to heaven nor be allowed to stay in God's Kingdom. That is the underlying message of the story for us.
It also shows that God allowed him to have free will to make a choice, stick with it and suffer the consequences. The same goes for us. Adam and Eve did the same thing in essence. They made a choice to disobey God and follow Iblis instead and they too were kicked out of Paradise for it but unlike Iblis, Adam and all his descendants have the ability or chance to redeem themselves by killing their Ego's, reforming themselves and submitting to God.
As for those who do make it to heaven, they will have purified themselves to some degree while on Earth (observing zakat) and will be further purified by God on the Last Day. (2:174,3:77,7:42,43) Who knows, at that point we may not have the ability to disobey God anymore, nor even the desire too.