"thinner" is not a universally superior quality. It also means "more likely to get bent or broken" which implies "more likely to need replacing" which is one of the direct aims of this legislation.
"Apple’s lightning-cable product page contains over 2,300 negative reviews of the lightning cable, with an overall rating of 1 out of 5 stars"
Lightning connectors do have the advantage you can safely stick a toothpick in them to remove lint, I don't know if lint building up inside the socket is a problem specific to lightning though.