The ability to transfer channels without an on-chain transaction is on the way.

When you can rent instant liquidity when needed, and return it when it's no longer needed, all without any on-chain transactions, a lot of the current problems with onboarding new users with non-custodial wallets will be solved. 

Lightning is cool, but still very much beta software and not ready for mass consumption by people that use 0000 as their PIN. 

For some people, right now, a custodial wallet where someone in support can help them when they forget their password is not a bad compromise.