That can certainly help, but even just being able to send money to people over the internet, easily, and with low fees is pretty enticing.
Less so at $5-10/transaction though. For example, a #signet is about $50 after shipping, so that'd be 10-20% in fees. Not an attractive option.
As long as people are willing to have someone else custody their money, lightning solves this. Another thing that'd do it is if we hit critical mass where people frequently hear things like "can you just send me some bitcoin [over lightning], I don't have PayPal [anymore]?"
I guess that's just it. I want it to be easier to get into bitcoin than to sign up for PayPal!