If you stop and look at how many Motherboard manufacturers there are and how many chipsets each put out. Then look at low many boards of each chipset they put out, I think it is unreasonable to expect Microsoft to have drivers for every one. If you add in all of the graphics cards there are, Lan and wireless manufacturers, there are millions of combinations of hardware in a computer possible. No one could expect Microsoft to have drivers for every single combination possible.
There is a reason you can get drivers from the manufacturer's web sites. The hardware manufacturers are responsible for providing drivers for the products they manufacturer. Microsoft has done a good job of providing drivers that will work on most components in the majority of computers. But, they can only provide the drivers provided to them by the manufacturers. Microsoft is not responsible for providing drivers, the hardware manufacturers are. If you consider the millions of combinations of computer components out, you would have to say Microsoft has done an excellent job of providing drivers. Anything not provided, it is your responsibility to find from the manufacturer. To expect anything else is unreasonable.