The lottery could really represent any tradition or practice that now seems outdated, meaningless, or even inhumane. The story conveys just how important it is to keep evaluating traditions for their value and not simply to continue them because they are traditions.
Once upon a time, slavery was a tradition. Obviously, that tradition was reevaluated and considered to be inhumane, and so it was done away with. There was a time when women's subservience to men was a tradition; women had to fight, tooth and nail, for the right to vote. That tradition, of the legal submission of women to men, was reevaluated and cast aside. (Of course, racism and sexism still both exist.) Racial segregation was a tradition for many years, but "separate but equal" was found to be an impossibility, and so the country underwent the process of desegregation. Not so very long ago, same-sex marriage was banned, as marriage was traditionally something possible only for a man and a woman. However, that tradition was questioned and the Supreme Court decided that it was discriminatory, and now we have marriage equality.