Yeah. its better to have 256x256 if you want better texture appearance. But if you want detailed textures, prefer to use 512x512.
btw, 256x256 is 2 times bigger than 128x128 and 512x512 is 4 times bigger than 128x128.
It's not so much about what they want as to what they can afford. Users will tend to start with 128x128 and skip the middle ground when they update, preferring to go onto 512x512. 256x256 is the middle resolution that isn't too desired.