Charging the Li-ion battery pack with our charger takes several hours. Question: Can't you make a charger that does quick charging, maybe half an hour like with NiMH batteries?

Short answer: Until 2021 = No. .... now Yes, read here

Long answer: There are two types of Li-ion cells available on the market: High current, low capacity and low current, high capacity types. We want long runtimes for our lamps, so we use the high capacity type. The current capability of these cells is sufficient for our lamp heads, but limits charging time. The charging scheme used for Li-ion cells takes its time, read this info for details. Increasing the charging current only marginally decreases charging time, but reduces cell lifetime. Cells for power tools are a different thing: They can be charged and discharged quickly, but have only half the capacity for the same battery size.