God has made every thing with a purpose:

God almighty had made every thing and phenomenons with purpose and he (Allah/God/Nature) hadn't created a thing without purpose.

Every thing small or great even microscopic render their part in this universe and lives, living in and out in the greater horizons. 

Take for instance, windstorm, when it blows human and animals seek refuge to safer places, while storm is rendering a wonderful service. It (storm) take away all dirt,trash away from streets,woods,top of roofs and from the depth of seabed to surface and thus make these thing able to be tidy and clean and place to be lived. Storm cut the huge trees,bushes short, shake the branches to release their burden of fruits and seeds on bed of earth so that new,plants,trees and grass can substitutes the older one. The fallen branches of trees and seed fertilize the soil and thus energized it again.
The insects and microscopic organic life compost the waste and turn it into soil again.

Even low mind and weak human and animal have their role to play in the world, though they always being condemned,persecuted,rebuked and menaced.

 Take for instances, if their weren't people of feeble mind and physic who render the minion and service jobs.If there were not people of ill will,insidious and evil minds, how conflicts arises and created millions of jobs in conflicts areas and zones. In matter of facts conflicts,disagreements are the main wheels which are running this world and universe? Take the conflict scenarios out off society the world will become stand and still, many thing would have and will disappear.

The clever people and animal make use off people of feeble mind and physic and things to not only benefit the clever but as well to the benefits of weaker people and animal. such examples are scattered around us to observe and we observe them daily.