What you say isn't wrong, but it isn't helpful. This is not about technical features, it is about profitable and less profitable phones. iPhone and comparable phones are more profitable, and the simple, cheaper phones are less profitable. And Nokia sells a lot of phones that are technically smartphones, but fall into the "less profitable" category. Over the last year, the number of Nokia phones that are technically smartphones has grown by 61 percent, with a massive drop in average sale price. That shows that the growth in smartphone sales didn't happen because Nokia moved customers from buying less profitable to more profitable phones, but because Nokia sold to the same customers at the same low prices, but selling them what is technically a smart phone instead of a dumb phone.
In five years time _every_ phone will be a smartphone. And all those people who today buy a cheap dumb phone to just make phonecalls will instead buy a cheap smartphone just to make phone calls. Nokia will sell 100 million smartphones instead of 26 million, and they won't be one penny better off for it.