Suffering - 3 reasons

Three reasons for suffering that are over-arching: 

1)  God will be glorified:  in some way… though God could have been glorified in a world without suffering—this is why I believe there are a few other over-arching reasons that relate to this.  Jesus said about the blind man being blind was not because of his sin or his parents but that the “works of God would be revealed” (John 9.3)—this will be the case in the resurrection, but prematurely in this case. 

2) suffering is due to and a reminder of the consequences of sin, not necessarily personal sin—though possibly it is —but because of sin in the world and its impact on creation (see Romans 8.18-28).

And, (3) God created man with a measure of free will which includes the capacity to sin (free will in the new creation will not include that capacity because it will not have any of the suffering).  God could have created such a world because such a one is coming, yet he created this world instead that includes a measure of free will with sin and its consequences.