Why the full driver matters on the 750
The automatic document feeder lets you scan a stack of pages in one pass, and the duplex unit prints on both sides without you flipping the paper. Both are driver-level features: the software has to know the hardware exists and expose the options in your print and scan dialogs.
Install the Basic INF driver and you get single-page printing only. The ADF and duplex options will not even be listed. You would effectively be using half the printer you paid for, which is why Full Feature is not really optional on this model.