It's a trade-off.  The filtering (introduced in P7) was meant to help avoid jaggy
edges, and to avoid moire patterns and other 'aliasing' artifacts on
detailed textures. 

The problem is, sometimes you want fine details and aliasing isn't a problem.  
I'm in this camp, so I always turn off the filtering.

Another option is to set Min Shading Rate very close to zero (as in 0.1) in the
render settings.  This also sharpens up the picture.

My python page
My ShareCG freebies