These 21 channels just let you open a channel and transact with one person (apparently unidirectionally). That's been in Bitcoin for a long time, but no one ever develops uses for it.
The LN will allow a person to open a channel like this and then send a payment to someone they haven't opened a channel with. In practice, the node the payor opens a channel with will have several channels open and payments will be routed between numerous payment channels until the destination is reached. This could take 10 hops, but it will be super fast because no confirmations.
By 21 adding this, they are simply incrementally building up to the eventual LN. It's a good step. Also, it's a good way to show the need for the LN; once people use this and like it, they will critique it for being limited to payments with only one person.
So as you can see, Lightning Network is still the best way to scale Bitcoin to VISA levels. LN is unavoidable if we want to see Bitcoin grow worldwide without massive datacenter-running nodes, and because of this there is a lot of people hating, because they are mad that blockstream came up with this before them.
I totally agree. Lightning Network will give Bitcoin an incredible push.
21 inc. it's version however will also find it's users I believe.
I also found a great explanation of LN on letstalkbitcoin.com
Defnitely worth a read if you are not that deep in the tech (I belong to these guys ).
But it's a massive wall of text, so take your time.
The Lightning Network ELIDHDICACS*
(Explain Like I Don’t Have Degrees in Cryptography and Computer Science)
https://letstalkbitcoin.com/blog/post/the-lightning-network-elidhdicacs