Sand dunes are the symbol of the Sahara desert. Minecraft deserts are just split into two different kinds. The plain beach sand desert with cactus and the Mesa biome.
first of all. Sand should be updated like snow. The higher the layers of sand gets it acts as a sort of stare block. Meaning that you could walk up sand dunes easily it will just take awhile because of their size both in height and width and length. They should also be somewhat in a line to create a wave effect. Minecraft sand is a stagnant Block that only moves by gravity if there isnt something under it. Updating the desert biome and bringing in hills upon hills of sand dunes at various heights would Make the desert biome much more awesome to explore.
•Cactus is not in every desert. Just in America. American deserts don’t just have sand and not every desert does. Deserts are defined only by the lack of humidity and moisture making it difficult for plants and animals to survive.
•Sand color. Not all sand is the same color. We have two different types of sand like the red sand so adding more that essential functions the same way, just a different texture doesn’t over complicate the game. Sand can be dark textures or bright colors. There is even blueish sand and gray.
with all of these things addressed you could have multiple types of deserts like the ones on earth. There are four major types of deserts on earth but we only need to address three. Subtropical (Mojave, Sahara, and sonoron), costal deserts, and cold winter deserts.
subtropical deserts could be broken into two biome models after the Sahara and Mojave (one being tailored toward the sand dunes, the other to a dry environment capable of having plants such as cacti)
The costal deserts could be modeled after a normal environment minus the moisture needed for plants. There are mountains and cliffs along with sand dunes.
the cold winter deserts are usually caused by the rain shadow effect of mountains blocking any rain. You could have a mountain range incorporated with the edge of this biome essential creating a valley of sand and rock. Each desert could have a new colored sand and even make room for new animals, mobs, villages and villagers and even dungeons.