It is know fact these Lighting Network "hubs" work as centralized servers where once users are under certain hub operator they have incentive to stay there and doing microtransactions only there rather than make another Bitcoin onchain transaction to settle funds and open new Lighting Network hub with another Bitcoin onchain transaction (probably expensive one if Core is right).
There is an incentive to run a hub, not a incentive to use one (from what I know). What are you talking about? This might be off-topic but I'd like to hear the answer.
Well right now it is the only easy way to legally buy bitcoins in the United States.
Where else are they suppose to buy them?
Buying Bitcoins on a website is one thing, using it as a wallet is another. I think that they should remove Coinbase or list it somehow differently (there were discussions on Github apparently).