The basic idea is that we will need a custodial solution because we may not be able to scale lightning to 8 billion people. Using these e-cash “banks” is currently our best approach. The protocol is much more efficient und quicker than lightning. It has the advantage that the custodians (mints) can not identify who is paying, I.e. they can’t censor a single user. In that respect it is more private than custodial lighting. Still, there remains a risk of rugpulls since the underlying lightning bitcoin is held centrally as with any custodial solution. 

 Minimum 5 "custodians" required to liquidate the mint.  Not foolproof but if custodial members were rotated yearly it adds a lot of complexity and effort to collude. 

 It's too complicated for the average user . I can hold my BTC privatly on my own.
There's already wallets like Alby that are not used by 8 million people. 
There are people that will not understand this and I can not see it being adopted if BTC is accepted by the average person. I can't see an apple cart vendor using this.