Before I got my first Android phone, my phone book was stored in featurephones with proprietary address books that couldn't be accessed without going to a phone store. Now my address book is everywhere with internet access. Whether I'm calling from my phone or a web browser, I type in a name and it just works.
The people who don't want this experience are a small minority.
With the older iphones, the phone book was backed up every time you synced. The phone numbers are still accessible on the computer and you could even get vcards from it. Then, when you upgrade (like I did from 3GS to 4S) transferring numbers was a snap: just connect and hit sync.
Note that no phone numbers were stored on google's or apple's servers. A very significant portion of the iPhone crowd still sync via cable.
The people who don't want this experience are a small minority.