Gabi,
I see it like this: Apple marketed its iPhone product as a smartphone, as a device which will fulfills one's mobile "computational needs". They didn't use such words, but in context of the smartphone market, there is this expectation when buying the device. Now, for many people, basic mobile phone need is to be able to manage one's own crypto-currency wealth. By them not allowing this, they are restricting my ability to handle my crypto-money when I am not at my PC, which can potentially lead to a financial loss for me.

Of course, I can buy something better, but that will mean additional financial burden for me, right? Because I can't sell my 3-year-old iPhone for a price, that will allow me to buy equivalent smartphone from other company. I probably wouldn't buy an iPhone, had I know at that time that they would not allow such an essential functionality 3 years later, but how could I predict that. I am just not so rich so I can buy new smartphone anytime I want, and why should I? I also invested additional money to buy other apps, to their ecosystem, and that would be another loss for me.

To sum it up, I think your argument is valid only for a new smartphone buyer.