There are many such structured programs that focus on child development, offering parents the opportunity to more easily follow their child's developmental progress over time. A safe environment is created for kids to attain the motor skills and confidence they need to grow and explore the world around them. The activities are planned and tailored to age-specific groups, making it easier for children to achieve milestones. These programs are fun for kids and allow them to interact with each other. Parents may also find the social atmosphere pleasant, exposing them to other adults with same-aged children and common life experiences. Unfortunately, children also share germs quite commonly in this environment, increasing their exposure to infectious diseases.
These exercise programs, however, can be expensive, but are not mandatory. An analogy I like to use is getting shoes for an infant. It is not necessary to spend large amounts of money on fancy footwear. Young infants only need something to protect their feet. Fancy shoes do not make them learn to walk faster. I feel the same about exercise programs for infants. Your child's pediatrician can share with you various activities your child can do at home, providing similar stimulations and challenges.
Overall, I think exercise programs can be exciting for both toddler and parent, but in my opinion are more icing than cake. Kids who do not attend these programs should still develop at a normal rate. I am not aware of any study demonstrating that children who do an exercise program have distinct advantages over children who do not.