It was simple. It got job done of adding and dropping. Now there is ten options to do one simple thing.
Smartphones existed before 2011. Casual users stayed away from it because of it being too complicated to use. Than came touchscreen phones which has a simplistic UI. It was so easy. Every Tom, Dan and Harry started owning one. It ate up the market share of Symbian.
Simplicity is way to future. Make things complicated. People will stay away from you.