The sooner we accept that Bitcoin cannot handle the entire populace on-chain, the better. Free markets are trial-and-error based. If Bitcoin has erred as electronic cash, then it's down to us to see which change in a crypto-protocol would make it look more like cash. Maybe there is none. Maybe it's dynamical block size. Maybe it's tail emission. Or even a compression method we haven't even thought of. In practice, we can see which is more recognized as cash.
What are the disadvantages of dynamic block size and tail emission? I also wonder what are developers reaction to the recent fees that spikes due to Runes, I didn't find any discussion about that in Bitcoin stack exchange, Github, or Linux foundation.
But, as the fees is keep declining, they might think it's not needed yet.
LN isn't going to solve this if opening and closing a channel costs a week worth of food.
LN isn't going to solve because it would end up like on-chain. 
Lightning Compatible: Different from existing token standards, Runes can be sent and received on the Lightning network, for faster and less expensive transactions.