Trademark is a privatisation of vocabulary. To be morally justified, it must have a purpose for all, not just for the trademark holder.
What is the common justification is as a proxy for characteristics and quality of the trademarked goods.
But when the trademark holder decrease the quality, or change the country of origin, and keep using the mark to use the goodwill it represent, he should lose his trademark, because the trademark is now used only for his benefit, as a mean to lie to consumers. Of course, morality and business are distinct worlds ...
Now, iphone means apple for you. It meant something else before (from wikipedia : The first iPhone model, released by Infogear in 1998, combined the features of a regular phone and a web terminal).