The reason charging at these fast charge stations only goes to 80% is rudimentary.
Li-ion in a vehicle ...of any kind....
have two levels to watch for...
the first is more important...

1- do not let the charge drop below 20% ..
repeatedly letting the battery bottom out or come close to it can brick the bank of batteries into lovely expensive doorstops VERY quickly....
as in...turning your brand new batteries into junk if you drain your batteries to low.

2- completely topping up your vehicles batts wears at the upper end of the charge...
charging to 80% is recommended for prolonged battery life...
It won't hurt or kill your battery bank to fully charge it if you do it now and then...but it is not recommended if the desire is proper battery lifespan.

With constant innovation into better batteries that hold longer charges ...that take up less weight and space... the loss at the upper and lower end of the charge ..for li-ion models will be more and more non relevant ...

New tech innovation in batteries and what will be the "future"...
Is all fine and good...
and I am sure it will happen...
But it is not only speculation....
Such new...better...cutting edge alternatives are a LONG way off from affordable production and implementation on a mass scale...

Look how long it has taken and the cost for those tesla batteries for the customer...

My bike is no different...
both banks of batteries ARE half the cost of the bike.
banks of such types of batteries for vehicles are expensive...right now...
when production becomes faster and supply is beginning to saturate the market...price goes down...
Like for most things...
At which time you will likely see the "cap" being reached on size, weight, and charge range ..flatten out.
At which time you will also see the beginning of demand by the consumer for more out of their batteries.
At which time you will probably see the implementation of "the new" form of battery which will replace the current top-end batteries.