First, I don't think it's certain that the features you cite are the most in-demand. I haven't seen any survey data to suggest that they are. That being said, people have been flocking to the iPhone for two reasons above all others... 1) Because it's an Apple product. 2) Because its interface is an unrivaled user experience in itself.
Never underestimate the power of the user experience... because if THAT doesn't work, it doesn't mastter if you have 30, 300 or 3000 features. They'll all suck if the user interface sucks.
Apple tends to release updated hardware/software as they gather more data from the market from their initial "feelers". It works like this... they put out a minimalist product with few but well designed features. They get feedback. They make revisions, additions, etc. based on that feedback, and gradually start introducing other models. This strategy has been so successful for them and is at the core of what made Apple come back from the brink of extinction.
So why don't they release more at once? There's a cardinal rule in business... never lead with your absolute best idea. If you do, how do you top it? People will only be disappointed from there on... and that's what leads to very short product lifetimes. In order for Apple to get the most out of five-six years of iPhone R&D, they're doing what they've done for ten years... making gradual innovations. Microsoft tries it the other way around and now that strategy is starting to hurt them... they put all their eggs in one basket. If that one basket fails to impress, they've got nothing else... and just wasted a decade worth of development only to find out at the end it's a bomb. That's just plain stupid.
These are not major complaints. A MAJOR complaint would be one of the incorporated features not working as promised. Of the features that are integrated at present, they're designed in a way that seriously raised the bar on usability... Visual Voicemail, the phone handset interface with the "flip"-able keypad and mute/hold/conferece/call-waiting interfaces... minus some minor implementation complaints that require very small refinements to address, iPhone is by and large brilliantly designed.
MAYBE people CONCERNED with VOICE DIALING shouldn't SPEND all their time IN THE CAR on A cell PHONE because STUDIES SHOW that EVEN using HANDSFREE puts a DRIVER at SEVERAL TIMES more RISK for getting into AN ACCIDENT because your MENTAL FOCUS is DIVERTED! Oh AND by the WAY, did you EVER notice HOW DISTRACTING and ANNOYING it is WHEN PEOPLE decide to EMPHASIZE WORDS all the time in CAPS as IF we'RE TOO STUPID to UNDERSTAND your MAGNITUDE OF CONCERN in a given SUBJECT MATTER?
