If we can go back to Godhead from any mode then what is the need to come to goodness?

From: sccd

In one of the lectures Prabhupada says, “The first step is given there, that sva-dharmäcaraëam. Sva-dharmäcaraëaà çaktyä. As far as possible, be situated in your natural life. Natural life means there are three modes of material nature. So somebody is affected or infected by some modes of material nature—sattva-guëa, rajo-guëa, tamo-guëa. So the çästra has made the path so clear that in either of these infection, either sattva-guëa, rajo-guëa, tamo-guëa, you can make progress spiritual life. Because we must be in either of these. Just like a train is going on: there is first class, second class, third class. So because the train is going, either you place yourself in the first-class compartment or second class, you will go. You will go. It is not that because you are situated in the third-class compartment the your train is not going. No, you can go. Similarly, Bhagavad-gétä has taught that one can go back to home, back to Godhead, in any position, provided he knows how to tackle the situation.”

my question is if in any modes of nature we can go to Sp world then why should we aspire to come to mode of goodness in D.S.?