A great garden design will have permanent pathways, and stepping stones…for walking and stepping. If garden beds, flower and vegetable, are kept narrow enough, then there is less temptation to walk on the soil of the bed. If the area is too wide, it’s best to place stepping stones.
Most plants like well drained soil. Walking on the soil compacts it and has an effect on the drainage. Compacted soil also has less oxygen and makes it more difficult for plants to grow.
For more ideas on garden design, see Garden Design Ideas