Be honest, you only got it if you did for the "free wii-mote".
Wii sports was like Twilight princess, released on the wii's debut to a world which would crave it enought to spend over 350 pounds to obtain a wii. And most people who buy a wii will think, i need another controller to have proper fun. So they will see wii-play sitting there in its box with a wiimote at the front and think. Blimey! A game and a wii mote, that means i get something extra when all i aimed to get was a wii mote and so the game gets bought.
But to be honest, with the rubbish game quailty, i think your getting the game free.