Most people view leotards as barely underwear. In fact, those that do not understand the reasons why leotards are required attire for some athletic classes often ask why anyone would wear "underwear" or a "glorified swimsuit" to participate. Actually, there are very good reasons why ballet and gymnastics leotards are the required uniform.
Streamline the Human Form
Dance and gymnastics deal a lot with aerodynamics. If you are wearing a ton of heavy sports clothing, you cannot move or bend as freely as you would in a leotard. You cannot flip, spin, turn, or jump as high when the clothing you wear is adding more drag than lift to your body. There is a lot to be said about the science involved with these sports and their uniforms.
Allow Teachers and Judges to See the "Lines"
In ballet and gymnastics, teachers and judges want to see the imaginary lines your body draws in space. The movements are supposed to create perfect visuals that appeal to the linear brain. Wearing a leotard allows teachers and judges to see if you are executing those movements and forms with precise accuracy. If not, you have to be corrected or penalized, depending on which sport in which you participate.
The Professionals Use Them
Those that came before you, for as long as these athletic options have existed, wore skin-tight clothing. If you plan to take your gymnastics skills to the Olympic level, you have to conform to what the Olympics deems appropriate as a team uniform. That is always the leotard, although you may be able to personalize it in small ways (and only if the entire team personalizes it the same way).
You May Find Leotards Very Liberating
Many dancers and gymnasts find that leotards are very liberating. They are not nearly as constraining or as uncomfortable as you might think. At one point, the body suit became a very fashionable piece of clothing, and it was modeled after the leotard!
There is a lot of stretch and give in gymnastic leotards, allowing these pieces of clothing to move with your body. It tends to make you feel very sleek, like a leopard slinking through a jungle. You can choose from a variety of fabrics too, including 100% cotton, nylon, and polyester. All will have a mix of spandex fibers to give you plenty of room to move. For more information, contact a business such as Dancers' Place.