I discovered that just making new normals for them made them look a lot better. Softening the gloss on the grass and such and sharpening certain edges. It's sort of a subtle change, but especially with higher texuv tiling, the effect is very pronounced and makes the terrain a lot cleaner. Some tiles, like the Space platform ones with obvious black aliasing lines from cobbling together aliased images, should be outright replaced. Most of the doodad textures should also just be outright replaced. A lot of units might not need their textures replaced, just their normals modified.
These are from an experiment I made early last year where I was testing how normals behaved with the terrain.
High values in the normal result in business and is really ugly in sc2's limited engine. A critical lesson that Sins taught me is normal maps hate being detailed, especially with DDS compression. DDS compression is something you'll quickly come to despise.
It still looks a bit like chocolate, but it blends OK with the existing textures. If I can somehow selectively sharpen the cracks and smooth out the noise, it would look a lot better.
This jpeg does it little justice, but what really matters is how hard it is to get normal maps to look good through diffuses.
Refine it down and you can get something like this.
Compare that to the default.
Not perfect, but it does make the existing texture appear slightly more higher fidelity. My main goal was to get rid of blurriness that comes as a result of bad normal definition.