In fact, I seem to remember that people were pretty much immediately complaining that there was no (official) way to bring third party apps to the iPhone (except for web apps).
If I remember this was also a major criticism: Some other phones at the time could install third party software, the iPhone could not.
However, despite the ability of installing third party apps existing in many phones, that never really took off before the iPhone SDK came out.
(Also, the iPhone did have a relatively slow start. It sold well and along with what Apple was publicly stating as its goal, but it took a generation before the phone really did take off like a rocket.)
If I remember this was also a major criticism: Some other phones at the time could install third party software, the iPhone could not.
However, despite the ability of installing third party apps existing in many phones, that never really took off before the iPhone SDK came out.
(Also, the iPhone did have a relatively slow start. It sold well and along with what Apple was publicly stating as its goal, but it took a generation before the phone really did take off like a rocket.)