To me the greatest strength of Bitcoin is that its uses have changed over time but its core principles have not. Initially many saw it as just a peer to peer payment system but in reality it has gradually evolved into a global store of value. So this is not a departure from the original purpose but a natural evolution and even with solutions like the Lightning Network, the payment opportunity is still there. The only difference is that now many people are more comfortable holding Bitcoin as a long term safe asset than for everyday transactions.
No matter how much we try to justify or refuse to admit it, the truth is that Bitcoin has drifted away from its original purpose. Today, most people view it as an asset to accumulate wealth rather than something to spend, let alone use as an everyday payment method.
In reality, people do not want to spend Bitcoin because they see it as a waste, not because the network is slow or transaction fees are high. Therefore, even if solution like the LN become widely adopted, it will be very difficult to change that mindset.