Perhaps because he didn't have enough confidence in his ability to score from there, so decides to cheat and goes to ground in the hope of having a better chance of scoring from the penalty spot.
But he doesn't cheat, he's clearly fouled, he'd have been be a fool to try to stay upright, proven by the ref's rapid decision.
I am sure, deep down, most enjoyed Suarez's act, I have seen no negative comments about Balotelli's ninja assault and that had, potentially, far worse consequences. I watched Bradford and endured an absolutely dismal game of hoofball and a 1-2 home defeat. It was only after the final whistle blew that I got my money's worth and fondly remember it as a good game.