For the same reason people lined up around the block for the original iphone, which was a poor excuse for a "smartphone" at best. The average Joe consumer doesn't want all the capabilities of Android, and would rather download flashy-looking apps with shiny-looking icons, or games which involve swiping your finger back and forth like a madman, and be sure to show off his toy to fellow hipsters.
WinMo and BBs at the time were a poor excuse of a smartphone. I still have nightmares about them.