Isometric icons are an evolution of the flat design trend, flat 2.0 and material design. The 3D to 2D design still uses clean and simple lines and styling but with a little more depth. Color palettes are frequently derived from flat and material as well.
Visual hierarchy is the order in which the user process information by importance. The visual hierarchy may seem to be oriented only to the aesthetic aspects but it’s not like that.
The key to every great design is the organization of its information.
Spacing methods and layout grids define structure hierarchy and rhythm in your design.
When correctly used, they reduce decision making and help establish a rational approach to type scales, positioning, sizing and spacing.