Wouldnt you want to have a motherlode hoarded when supplies dry up 100 years from now, a commodity that fuels advanced avionics?
It does unfortunately mean that you need to excavate a lot to mine it which is not great for the environment either (even though lithium is currently key to most renewable technologies)
The lithium mine in question is 0.22%, doesn't seem like your range is that typical.
I agree it will have limits, I doubt I'll see long flights like 200 miles. But I see no reason it can't improve by 10% a year just like the batteries. I believe the ones in service are using lfp batteries, which are safer than lithium batteries, but also have lower energy density - and these have gone up over time too in energy density.