Just How Many Apples Do We Need?

I read an article this morning about Apples. It never occurred to me until now that there are people who spend their working hours developing new varieties of apples. My question is why? Just how many varieties of apples do we need? This new apple is called the SweeTango. I reckon it has something to do with it's sweet and tart flavor yet it apparently maintains the crispness of the Honeycrisp which is wildly popular. Who knew? The SweeTango was made by crossing the Honeycrisp with the Zestar...