iPhones couldn't run Flash (which powered all of the interactive content on the internet at the time), couldn't send MMS (which was the way everyone shared photos at the time) or run apps (which was how feature phones added functionality at the time).
"Why on Earth would anyone want one of those!?" was a pretty common reaction, yet they still sold like hotcakes. In the case of Flash and MMS, the whole mobile internet changed to suit the iPhone. In the case of apps, Steve Jobs finally relented, leading to the single biggest software marketplace in the world.