Corrected entry: George is in a life crisis that leads him to contemplate suicide at a bridge. Clarence shows George how much George's life means by showing him how the world would be. if George wasn't born. But Clarence doesn't show George what the world would be like if George completed his suicide. Clarence gave reasons why George should have lived up to the bridge scene. But Clarence doesn't give reasons for George staying alive beyond the bridge scene. Life insurance and remarriage are already two benefits to the family's problems. According to the plot, George's dilemma is whether to jump off the bridge or not.
Correction: You're missing the point by a parsec or so. Clarence is there to SAVE George's life, to give him a reason to go on living; indeed, Clarence's future as an angel depends on him doing so. He's not there to just dispassionately show him the options and let him kill himself if he still wants to; that wouldn't exactly be very angelic, would it.
So true and I think this plot was done in a Christmas story.
Correction: Because Clarence gets George to admit that suicide is not the solution George is looking for. That's when George says, "I guess it'd be better if I was never born," and that everyone in his life would be happier and better off if that had been the case. So Clarence gives him that wish, and it works. George ends up wanting to live again and is rewarded.