Money, they hope you enter more classes, the shops hope you will buy a different engine/kart for the extra class, they in turn sponsor the classes.
Same deal in Road Racing, for the better part of a decade, Animals were either the first or second largest class. One set of engine rules, 3 weight classes, light, med, heavy. Run twice either day. That now is up to 12, 4 cy classes, different engines, different rules. Last year at Daytona, they had 15 Animals, it used to be we would have between 30-40 Animals at each race. We raced Daytona every year since ’94, do we go anymore to race against 15 others, not a chance.
Now a question, is WKA still a member owned org.?