People are born with a lot of genetic variation. I realize that no matter how hard I train, I will never run 5,000m in less than 13 minutes. It's not a matter of increasing dedication or anything like that -- it's simply getting the right genes. Even in high school and college, you see the people with the best genes rise to the top with significantly less effort.
So why would I participate in something that rewards luck? Because it's not entirely luck, and the further away from an elite athlete you are, the less luck matters. A high school runner with poor innate running ability can easily beat the most gifted runner by working hard and training correctly. It's because even those born with low potential have a huge range in which they can improve, before they begin reaching their genetic limit. In fact, I would argue that very few people ever come close to reaching their limit.
So I can appreciate that even though there is still an unfairness in how hard different athletes have to work to achieve the same goal, the goal that matters in competition (winning) is really determined by those who are the most dedicated and committed at the more local levels of a sport. (Of course, we could get into the debate that hard work and commitment are also genetic traits, in which case the whole thing becomes a crapshoot, but I'll leave that question for another time).
Now, elite athletes are nothing like normal people. Almost every single one of them has hit (or is very close to) their genetic limit. They're at a point where more, or different types of training just won't do anything. At that point, "winning" comes down to a genetic lottery. Which is kind of sad, because these people have spent their whole lives working for something where achieving it depends mostly on chance. I assume most of them either don't recognize this or (more likely) don't care. There is a third option though... recognizing this and fixing it. This is where drugs come in. My first thought is that these high performance drugs "fix" what was never fair to begin with. But the problem is that sports weren't designed this way. When these athletes began their decades of training, they recognized what the rules of the game were. Like a board game, there's some element of luck and some element of skill. And because they knew the rules of this game very well before they began competing, I can't condone anyone using drugs to make the game more fair, because the other competitors never agreed to this.
Simply put, it's cheating. And the majority of the world (at least for the moment) thinks cheating is immoral. So we should continue to ban athletes that don't play by the rules of the game, regardless of the fact that they are trying to make the game more fair for themselves.
What are the pitfalls to breaking these rules? You're cheating all of the other players in the game, who never agreed to let you break the rules. You're cheating the fans of the game. You're stealing money (highly competitive sports have large amounts of money involved for the winners).
Now, if somebody wants to create a new game, with new rules, by all means go ahead. I personally wouldn't take an interest in this manner of competing, but I'm sure there are many who would. And they would be doing it morally.
Just my thoughts.