I guess most people are happy with the difficulty level as it is.
I expect there are some like me for whom it is just way too hard.
I expect there are also some who would like it to be harder.
It really can't be that difficult to allow 3 single player options - Easy - Normal - Hard.
I can't see the reasoning behind treating us all like communists with equal skill & reaction times. The beauty of humanity is that we are all different, and all have differing skill levels at different tasks.