I do think that the reason Apple presented us was not 100% compelling and after reading many reviews that seems to be the feeling, that doesn't mean the watch will fail, it'll be interesting how this unfolds.
The point of "needing " the phone or watch is pointed towards the fact that without the watch we'd still be able to get messages, control music, use Siri, etc. "need" in a sense that without the cellphone we'd be pretty much cut out of all this content and features, not that we need a cellphone to survive...but it plays a more important role, technologically speaking
Note: came back to say: have a wonderful day, How could I forgot that.. =)