If you assume that the same people who would buy the finished product will also buy the EA version, then there is no reason to finish it. However, if you assume only a small portion of the potential purchasers will go EA and if the net cost to finish it is relatively low compared to creating an entirely new game, then you have every reason to finish it. I.e. it's to make a profit. Plus they can then enjoy the pride and satisfaction of delivering a polished, finished game.