whenever I hear from anyone saying "USE LN"
Whoever tells you to just use LN without warning you that LN is in testing mode, that it's risky to use LN and that you should really use LN for now only on testnet is incorrect (to say it nice).
That is no longer true. It is sufficiently safe to play around it with the suggested amounts (up to $40) on mainnet. Heck, some people almost insist that you pay them only via LN for any smaller purchases now (even though on-chain fees play no role currently).
I think that LN will eventually be an important part of the overall ecosystem, but there are some downsides:
First, the biggest downside of LN is that the recipient has to have their LN node online and listening at the time of the transaction in order for the transaction to occur. This is fine for payments to web stores etc., but I think that it will largely preclude usage of LN for more peer-to-peer transactions (eg. forum trades). It would not be good if people were expected to use only LN, since that would result in almost all individuals using trusted-third-party wallets in order to accept payments.
Aren't we already there though? Given how many people use: a) SPV wallets (which are not connected to their own node). b) Online wallets. c) Exchanges and other services as their wallets; I don't see this as a real argument here. However, it is indeed quite inconvenient that you can't use LN without an active node. Watchtowers should help.