To monitor for fraudulent channel closes in order to be able to react in time to challenge them, it also requires you to have an always on-line node, or a trusted third party delegated to do that on your behalf. And if you want rapid/automated reaction to fraudulent channel closes, that node needs to have access to the private keys to your LN funds.
Then there are routing issues when the topography of the network changes with every transaction, and where the existence of routes is dependent on sufficient capital being locked up in channels.
There's a reason why there's 100 times more BTC locked up for use in Ethereum dApps than for use in the LN. Ethereum-based scalability solutions could, ironically, provide BTC with the scalability needed to gain mass-adoption as an instrument for peer-to-peer payments.
Then there's the lightning network, which allows you to transact BTC an infinite amount of times off-chain for next to 0 fees. I've used it countless time this year and the prior and have probably spent less than a dollar in fees total. A lot of crypto exchanges are implementing it too, which will drastically lower the fees on the overall network. Bitfinex has support for it right now. Kraken will support it this year