Yes, it's not easy to know what one really nees, this is one reason why people will opt for a single device - even a limited one - when offered with an overwhelming array of choices. I suppose that is one reason why the all-in-one holy grail of mobile devices will this year be communicators (and smart phones). If people don't know they really need a good PIM suite, they don't want to carry around a PDA. If people don't know they really need a mobile web browser, they don't want to carry around an internet tablet. There is the cost aspect too - a decent device with usable functionality costs a bit, and multiple devices tend to cost even more. (Oddly enough 770 + simple GPRS phone would provide a nice price point in comparison to communicators, the only catch is increased bulk.) If what people need on the move is just checking bus schedules, making a quick note or storing a meeting in a calendar for a later alarm, they will be just happy with a communicator.

On dependence on all new technology - well there is a price on forgetting previous forms of life, but technology answers some real needs as well: broadband for better quality of viewable media, lagfree communication; internet tablets for the same information capacity on the move; wireless connections for integrating all the gadgets we have to use day to day. When technology is widespread you are expected to have it to be a functional member of the society/your subculture. If I am working I have to use the cell phone, because if I'm reachable I can be asked for advice, opinions, and information, making the tasks of others that much easier, and speeding up our corporate processes...