Instead, the texture simply repeats less. In other words, a 1024x1024 texture has the same resolution and quality of viewing as a 256x256 texture file. The tiling just does not repeat as much with a larger texture file.
Then, it's likely a limit of the engine, one would assume. It's probably hardcoded, so that no matter the size, whether it be 1024x1024 or 256x256, it is automatically scaled downwards. Perhaps it has something to do directly with the tile size in Worldbuiler. Just a stab in the dark, to be honest.
Edit: Just had a look and found the exact same result as you. The resolution really doesn't seem to matter much, it simply tiles far less, the bigger it is. But, quite honestly, that makes it look far better. If you use textures that you've perfected, so they're truly seamless....it should look better than the old, low-resolution terrain textures.
An option is to divide it up into pieces and put it in that way and letter them so RobDirt1A etc.
This method works, but can be a little messy and will require more than a fair share of blending.
Edited by Pixel, 20 May 2014 - 03:23 PM.