There is many ways and tools to create low poly from high poly and there is InstantMesh, a free tool to create low poly versions, with controls, giving great results.
http://igl.ethz.ch/projects/instant-meshes/
Github and download
https://github.com/wjakob/instant-meshes
Damn! I’ve seen ALOT of modifications to blender’s Decimate modifier, but this thing is just something else, Thanks for mentioning!
You can also check BakeMyScan addon, which allows to use remeshing & retopo tools from InstantMeshes, MMGtools, Meshlab… directly inside Blender 
Damn! Would love to use that! Thanks for mentioning!