I think this thread has turned for the better. Mike has hit the nail on the head.......write a great song...there are no short cuts. Joe has also added that there is more to a song than just words and melody. Production is high on the list of requirements and that in nowadays pop can actually be the song itself. Also the performance counts for much of a songs appeal. Few people I know can tackle ALL of these crafts with the required expertise.
That is why teamwork is important.....while someone can write a great song ie words and melody it really needs a team to transfer that into a proper recording. As for the song being a hit......you have to worry about all the other things first.