I don't think it matters so much what a person was like, especially if they've changed for the better (fictional example- Darth Vader coming back to the Light Side as Anakin Skywalker). True, alot of folks are humbled by disease and hardship, even poverty. Through some ammount of suffering they see things as they are, are humbled, and value life more than they did before and tend to not take it for granted as much.
Was Reeve such a person? I wouldn't know. But it doesn't matter. He made up for anything he might have done by the life he led after the accident, in my opinion. Sometimes, as fate would have it, seemingly horrible things happen to good and bad people because it was meant for a turn-around to take place or for something to change in that person, even if its something as minute and untangible as a view point on life or a change in morals. Sometimes the change will never seem evident, but it happened, somehow, someway. Its only then a matter of the person using the opportunity and making the most of it for the better.
Christopher Reeve could have easily become an introverted, twisted man filled with sorrow and self-pity. He could have pulled the plug on himself, so to speak. He didn't do that, and thats what made him special, and he didn't keep his optimisim to himself. He shared what he was, and it benefitted and touched so many people.