Devdas was published in 1917. In the intervening decades, many things have changed, and many people have remained the same. Perceptions about the three principal characters: Devdas, Paro and Chandramukhi have changed. Because of the genetic linkage, the basic human nature of both Devdas and Dev D is the same. Both are alcoholic, a symbol of instability. But the environments in which they are brought up are quite different. This is mainly due to the changes in the attitude of parents (and therefore children) and the meaning of love and relationship. No wonder Dev D is not Devdas!
Paro and Chandramukhi are also not the same. Paro of Devdas is a lover. She does not get Devdas, but till the end remains his well-wisher. Paro of Dev D is a lover, and when she does not get him, becomes vindictive and plays the game of one-upmanship with him. Chandramukhi, both in Devdas and Dev D, is a friend and remains a friend. Devdas doesn't love Chandramukhi. Dev D, after initial hesitation, says he loves her. I am not sure if Chandramukhi also has the same feeling for Dev D. May be she is happy remaining his friend. The refusal for marriage with Paro comes from Dev D and not from the father (as is the case with Devdas). In Devdas sex is implicit, in Dev D it is explicit. What did Devdas and Dev D do when confronted with extreme distress? Devdas tried to reach Paro, but died on the way. Dev D went to Chandramukhi. She accepted him, still hoping Dev D shall mend his ways. Today's generation being more hopeful, perhaps Chandramukhi's approach seems appropriate in Dev D.
In the intervening decades, something has not changed, and that is the basic 'nature' of Devdas and Dev D. Both Devdas and Dev D love only themselves. Had they loved Paro or befriended Chandramukhi, they would not be so irresponsible. Their love/friendship caused Paro/Chandramukhi only embarrassment, still they loved him. That's why love is the most strange thing.