Most of transactions are one way payments eg. company paying employees salary, buying stuff in the internet and giving donation to a particular organizations. In LN, the amount of transfer is limited to available balance of each party in the channel. If the payment keep going one way the balance on one side of the party would deplete unless a significant amount is put in the channel in the first place. Eg. you need to put a significant amount of balance in lets say ebay so that you can pay with no transaction cost on multiple items. I am just saying the use case is limited, i am not sure to what extend it can take the load off blockchain. I just think increasing blocksize is still very much needed.

The other disadvantage is by using hubs we are most likely going to pay the fees in percentage instead of satoshis/transaction like on chain. The reason being the higher the transaction amount the more capital is needed by the central hub. So this very much limit the use case of lightning network for very small payment amount ie. microtransactions.