While users just want to do some simple things, they
do care about the downsides and annoyances (that we know grow directly from lock-in). FB people already grumble about privacy, the meaningless of 'likes' and 'friends', the annoyance of all those third-party apps spamming friends of the player, etc. They're ready for change. They may not care about '
how', but they absolutely will care whether the next destination has those problems.
Sure, you need to wrap features into the protocol that will appeal to FB people. You should absolutely take the opportunity to solve some real problems. But the open architecture is crucial to protecting privacy. Without competition, no flavor-of-the-month network has incentive to put user needs ahead of its own wants.