It's been well over five years since the Lightning white paper. By this point in Bitcoin's own timeline, the MtGox scandal was in rear view mirror; in another year, the Lightning network will be as old as Bitcoin was when Lightning was proposed.
If Lightning is going to provide the mainstream digital currency Bitcoin promised but failed to deliver, why is it taking so much longer for Lightning to be adopted than Bitcoin?
The internet itself at the backbone/isp level is a decent analog as ISP peering can be complex and often involve cost. It took awhile to get BGP right and determine the right cost metric for selecting a route.
There don't seem to be any blocking issues though and many of the large wallets have announced that they will be supporting it eventually.
Once it gets a few user-friendly wallet and merchant apps, I'd expect to see adoption. Especially since it's much safer for merchants as they do not need to wait for confirmations, and transactions fees are fractions of a penny so merchants actually benefit compared to creditcard interchange fees.