With all of the contestants being athletes, producers knew from the beginning it would need to be a shorter season because of busy schedules and the varying talent. With the show there are typically performers that make it into the finale with some dance background being professional singers, but with athletes you never know how easy or difficult it will be for them to remember all of the dances, therefore making it easier to have a shorter season. The main downside: you don't get as attached to the stars or have fun, themed nights.
Downsides of the four-night season
Typically with the 10 episode season, there are themed episodes where you get to learn more about how the couples prepare for their dances and what their favorite memories are. With the shorter season, they are eliminating two couples per night and it's all focused on the dance rather than the journey. Also, with the shorter season, you don't get to see the improvements from week to week that prove why each couple makes it to the finale. Some of the favorite couples that you would expect to make it further may get eliminated sooner because with a normal season they would last until week 8, but with the semifinals in week 3, there are fewer dances to enjoy.
In the typical season, the show waits until around week 5 or week 6 to begin trio dances and team dances, so the stars have to learn two to three dances per week.
Having a longer season helps because they have four weeks to become semi-confident in their dance skills. Dancing to two dances a night by week 2 can put a lot of strain on the stars' memory and could potentially mess them up. Many people can say that since they are athletes, they are used to high stakes and pressure, but the show is really about joining a dancing family, showing the world who you are, and proving that anyone can learn to dance.
Politics of the short season
The network wanted to test out the all athlete season, but because they weren't sure of how the ratings would be, this also contributed to the shorter season. ABC's lineup for the spring interfered with the long season, with "American Idol" premiering in March and "The Bachelorette" premiering at the end of May.
These two shows bring in the most views so they are a priority. The show is trying new things and testing the waters. This is their 26th season, but, in my opinion, if it's not broken, don't try to fix it. That said, the ratings may show something different. Later this year, they will premiere a juniors competition. Fans can likely expect a full season but with younger competitors as the stars.
