Frankly speaking I do not feel that the song "Jai Ho" is not one of best works of Rahman. If one has heard to his work from the beginning you would agree with me.
His first movie "Roja" itself showcased his talent and there are plenty more to mention. In Hindi movies you should listen to his work in "Jodha Akbar", "Rang De Basanti", "Delhi 6" etc. His work is so unique and refreshing. And the best part about his songs are that they introduces many singers making each of his songs special.
Oscar is an award that is made by the Americans and it cannot be compared to the other international awards. But Rahman has already crossed boundaries long ago and established himself as a successful composer. So, I don't think that getting an Oscar would make much difference to this humble man. He is a wonderful human being and very talented. And his humbleness would take him a really long way. We love listening to your work Rahman. You rock!!!