Facetime faced a patent lawsuit, and Apple had to change how it operated (to have it relay through its serves), making not that great as a direct communication standard.

Lawsuits tend to put a dampener on things, so there is that.

That was a last-minute uninformed decision about a completely new product. Swift's open sourcing is clearly planned ahead of time and has actual the full backing of the company.

I think this is one of those situations where the fact that they've failed to deliver in the past makes them far more likely to deliver this time.