From the summary:
The small battery pack also means faster charging times
That's not how this works. Charging time is unrelated to battery size, except that in a given amount of time a larger battery can take in more energy. You charge all of the cells in a battery in parallel, so unless your input power is limited by something, charge time is dominated by how long it takes a single cell to go from empty to full. The number of cells (i.e. the size of the battery) is only relevant to how much power your charging system needs to deliver so that all of the cells can charge as quickly as possible.
There's a little variability among chemistries, but to a first approximation, the Li-ion cells we use today all take about 1 hour to fill from empty, when given power at the highest rate they can handle without sustaining damage. And they can take it faster when they're close to empty.
If you want to minimize the amount of time it takes to add X miles of range, what you want isn't a smaller battery, it's a larger battery. Suppose you want to add 50 miles of range in two minutes. Assuming 165 Wh/mile, you need to add 8.25 kWh. In two minutes a low battery (say, 20% SoC) can add about 10% of its capacity, so to get 50 miles in two minutes at the assumed mileage, you need an 82.5 kWh battery, and a 250 kW charger.
I'm sure Tesla has done the math carefully and weighed size and cost against range and charge times for their expected usage pattern and determined that 50 kWh is the right balance. But a smaller battery doesn't reduce charging times. For a given demand profile, a smaller battery increases charge time and a larger battery decreases charge time.