The on-chain atomic swap (no Lightning Network involved yet) was executed using Decred technology ( https://github.com/decred/atomicswap ) and was preceded by a DCR-LTC swap ( https://blog.decred.org/2017/09/20/On-Chain-Atomic-Swaps/ ).
(De)credit where credit is due. ;-)
In particular, as coauthor of the lightning spec, I assure you that we're all working on bitcoin. Litecoin happened because it was trivial; interestingly, we've deferred Bitcoin mainnet because it's likely to attract real users, who'll risk real money.
I'm not familiar enough with LTC to say if this will continue for the future, but thats the standard argument in favor.
(Anyone with a passing familiarity w/ CCs would know this, but still, it feels like statements that are so blatantly counterfactual should probably be noted.)