CMOS NAND VS an Alternative NAND Structure
There are two reasons, in my opinion: First, the CMOS Version can be built without resistors (obviously), which is a huge advantage in integrated circuits. So huge, that this is actually enough. Integrated resistors are gigantic in size, compared to the tiny transistors, which are needed for the NAND. Depending on the needed driver strength, these transistors can be really, really small.
Second, the CMOS NAND uses no static power, since either the pull-up path or the pull-down path is of high impedace.