They just had an entire iOS cycle that added barely anything if you didn't have other Apple devices, everything is centered around you getting several Apple products now.
The watch will never be fully functional without the phone, this has been the concept of wearable from the start. As it evolves, some functions will become standalone I'm sure, but I doubt most of it will work without an iDevice in Bluetooth range.
They're mostly leveraging the iPhone's popularity/market share to sell everything else, but the strategy works starting from any one device to another since they're all interconnected into the same ecosystem. iPhones are just ridiculous sellers and people are more likely to have that than the other products.
The interesting point of the potential of the watch though is this:
^After seeing the thing in person I 100% believe some people will want to wear it regardless of the fact it's a computer. I really don't think being established in the iOS ecosystem is a prerequisite. Obviously most people getting the watch will be iPhone users already but now that I've seen how nice it is in person I have no question some people will *just want* it and make the switch because of it.
People feel they need a phone, whatever phone it is it's a somewhat logical enough reason, it's just thought of as a necessity. If the watch can trigger the
just want nerve, it can trump the usual logic, like making a decision with your heart instead of your head or something. People buy stupid things all the time just cause they want it, not cause they need it. If someone isn't wedded to Android or whatever else and lusts after the watch (and have the disposable income) it's not necessarily a going to be a big deal to switch for it.
...whether things will shake out like that with the general populace, who knows.
And as far as the whole keyboard subject, one trick with tiny keyboards like the MS Band's is autocorrect. So it might be ok for prose but I'm not sure it'd work for logins/passwords as mentioned. Anyway if you have the time to type that shit out on there in church you can probably just pull out your phone to do it much faster for anything longer than a few letters. You should have your phone out anyway with the bible app of your choice open to follow along with the pastor!