There are many articles about the AA filter out there, so it's use is no mystery. It is there to reduce moire, but it's drawbacks are less detail, sharpness and lower resolution. That is why the newer high MP cameras have no filter. Put the AA filter back on, and you lose the advantages of the higher MP count. Pretty simple really.
Yeah...that's pretty much all BS. There's just a hint of truth in there, barely.
An quality AA filter, with modern processing, reduces resolving power by just under 10%. However, removing the AA filter pollutes the entire spectrum with false information from beyond the spacial resolution of the sampled system.
So, which do you want? Do you want slightly lower resolution (10% is basically undetectable by eye) or a total inability to trust any of the image information you do get?
Most of the supposed increased detail from a camera that lacks an AA filter is just false detail being mistaken as actual detail by the viewer.
Ask yourself this question. If an AA filter did nothing but decrease image quality, why would camera makes put it into a camera thereby costing themselves money and buying nothing but lower image quality rankings?
The answer is simple - they don't. An expensive camera like the 7DII (which has the same size pixels as a hypothetical 50MP full-frame camera) has an AA filter because it is necessary to get the best possible image quality.