Yeah, I would almost never sharpen a texture in the mips - you generally want less detail as distance increases. However, IIRC, there are sharpening options in the DDS exporter, so you don't need to do it manually.
On the other hand, I occasionally will open up a texture and futz with the alpha in the mips, so that it will fade in/out according to distance.
I would also love to have an easy way to simplify shapes on textures in the distance. Check out this painting:
The closest tree has 5 or 6 colors in the foliage. The farthest ones have only 1 or 2. That is something you could maybe simulate by hand painting the mips in a texture, but it would be a pain in the ass. Having a tool that could slot textures into various mips and allow easy editing would be better.
The benefit is that you still have crisp shapes in the distance, just at the proper granularity. Scaled-down mip maps just give you muddy over-detail.