Problem is that even LN needs the onchain features to open and close channels. And despite the fact that I do not believe that this might be a problem in the near future, it's a fact that the more users the LN has, the more channels will need to be opened and closed. And when that needs to happen, and if the fees keep the way they are now, we will be waiting ages for channel open and closures and paying stupid high fees.
Certainly a correct answer.
I did want to add some additional information tough: it's pretty common practice to rebalance your channels, so if person A has a channel with person B (and A is using it to send funds to B all the time), B has a channel with C (and B is using it to send funds to C all the time) and C has a channel with A (and C is using it to send funds to A all the time), it's possible they can just rebalance their channels once in a while and closing and reopening a channel would only need to happen very rarely.
It is true, however, that at this point it'll cost you a lot of money to open a channel. It is also true that if you'll be using the LN only to send funds (and never receive) or if somebody opens a channel with you only to send you funds (which you'll never spend), you'll be forced to open/close channels on a regular basis.... But as long as you have a lot of channels already open, and you spend about the same amount as you receive, it *should', *in theory* more or less even out...