Would you wear a football helmet to play basketball? Would you wear basketball shorts to go snow skiing? So why wear gymnastic clothing for a ballet class?
Unique styles of clothing develop through attempts to improve performance and to meet the unique needs of the selected activity. Dance wear has evolved to meet its unique needs, just like football, basketball, ... In the early 1900's dance wear looked like swim wear, and swim wear looked more like a dress with bloomers. Both swim wear and dance wear evolved into body hugging shorts and top. Then swimming got the bathing suit and dancing got the leotard. But dance has many forms, each with its own unique needs. Dance studio wear is not a fashion statement. Dance gear is selected to improve performance. Even hair style effects performance. Hair is not warn up so a student can look like a ballet dancers. A student cannot dance like a ballet dancer unless the hair is out of the eyes for clear sighting (spotting) while turning.
includes falls (from standing to lying on the floor.) Obviously a dancer would get tangled up doing this in a traditional ballet skirt. Falls, often broken with an arm sliding on the floor, make long sleeves appealing. Tights without feet were developed for Modern Dance since it is performed barefoot. Then the desire to get rid of bulky layers led to joining the leotard and tights into the unitard.
is a form of movement that generates a lot of body heat. Fabrics are designed to release body heat. As aerobics became fashionable, dance wear became high fashion. Multi-colors, patterns, you name it and a leotard became created in it. Great fun for the gym, but not automatically appropriate in the dance studio.
needed shoes of incredible specialization. Ballet is circuit training. Ballet classes consist of repeating methodical exercise followed by rest followed by exercise followed by rest, followed by exercise... The ballet dancer must wear clothing that is not too hot during exercise but prevents too much cool down during rests. For this reason, aerobic gear may not be the best choice. Ballet wear must be also be extremely flexible and stretch. Ballet (before cross-pollinating with modern dance) was performed mostly in standing position. Without concern for falls, ballet evolved into sleeves of various lengths.
Unique to ballet is the barre work where cold bodies are gradually warmed. This has resulted in the development of over wear. "Warm-ups" are sweaters, tights, leg & arm warmers to be worn over regular dance wear until the body has been warmed up. They are also used to keep the body warm during extended rest periods such as between class and rehearsal.
The signature of ballet, the tutu evolved because there is nothing like a guy trying to grab gal before her body hits the floor and coming up with only a handful of skirt. But, tutu's are not class wear. They are costumes for stage wear. Class wear consists of tights and leotards.