Why are some of health insurance companies charge you some money at the point of health care services ?

If you are referring to the deductible amount or co-pay associated with health insurance coverage, this amount or percentage is used to lower ethical risk that comes from policy holders using their health insurance more than what they actually need. 

It also, lower the premium in cases like group health insurance, significant drop. 

For me, health insurance taken out to cover the cost of medical care, especially i can choose of my own doctors and specialists.

Because sometimes there is a miscellaneous not covered by the health care services specially not included in your cases and the other used to improve facilities. And when exceeded the limit.