Twenty or so contestants are divided into tribes, stranded on an island, provided minimal resources, and left to fend for themselves. They work together, but once every three days they go to Tribal Council and vote one person off, until there is only one survivor left. Survival skills are a factor. Physical prowess is important to win challenges and be safe from being voted off. And strategic thinking helps. It's fun to watch. Mostly.
The show is generally not about survival of the fittest. Many times, strong physical players are voted off early because they might be a threat later on; players that are well suited to the challenge and might have gone down as some of the best players in the history of the game had they not fallen victim to a group of physically weaker players banding together against them, before they then turn on themselves in the end.
I enjoy Survivor all the way up until the end. After 39 days, the final episode is settled by the last two or three players remaining, pleading their case to the jury for why they should win the million dollars; the jury consisting of the last 8 or 10 people that got voted out. To make it to the end generally requires deception and hurt feelings. At the final tribal council, the last players remaining, one at a time, often get gutted in front of everybody by hurt players looking to inflict maximum damage in turn for their betrayal. The winner each season gets a million-dollar check, but I doubt many of them get to walk away feeling very good about themselves. I don't enjoy that part. I wish there was a way to change the dynamics and make the ending more of a celebration of a game well played.
The producers of the show put together the cast of characters for each season. They don't know how the season will play out, but they can be sure to set up enough conflicting characters, enough of a dysfunctional family, that there will be plenty of drama. I think I'd rather see a competition between stronger players well suited to the challenge. Maybe one time they could select a group of Army Rangers to compete against a half dozen Marines, and a team of Navy Seals. There might not be as much whining about being cold, wet, and hungry. Actually, they probably wouldn't be nearly as cold, wet and hungry, being capable of building their own decent shelters, and better at understanding the resources around them.
I don't know how I could get what I would prefer out of the show without ruining it for everyone else and destroying its ratings though. Survivor has been on for 40 episodes, over the course of 20 years, and is still highly rated. I guess the show I just put together in my head would be the most boring, single-season, reality show ever.