Here's why- the governments wont allow it. Right now the U.S. government is working on bitcoin/cryptocurrency legislation that Steve Mnuchin (Secretary of the US Treasury) is putting together and recently said should release soon. I'm fearful of what's to come and bitcoin isn't even anonymous at the moment. Governments can kill the exchanges. Sure there's always over the counter, but that's not going to bring this to the heights we all hope it's headed.
Think of it this way. How many countries still don't allow for women to vote or even show their face in public, how many countries don't allow for freedom of speech, how many countries still don't allow freedom of press...and you think they'l be okay with a massive global currency they can't control what so ever? Not a chance.
I hope LN is something that stays on another layer and is used for anonymous transaction or something else is created so that bitcoin has both options..but making it fully anonymous wont work out well. As a financial advisor this is something seemingly obvious to me after spending over a decade in finance and seeing how this kind of stuff is received by governments.
Would love to be wrong or hear how it could still work.
Governments will always want to have control especially in the economic environment.
They will never allow an anonymous system to be established and let people transfer anonymously money to each other. This is not going to be transparent in their eyes.