Metamorphosis tells about the desperate struggle of a family fighting the effects of a tragedy brought on for seemingly no reason.  When Gregor transforms, his family is forced to deal with the repercussions, just as families had to deal with the aftermath of World War I which, to many, had seemed to take very many lives for very little reason.

I couldn't help but find a larger connection, however, between Gregor's struggles with his new body and the experience of wounded war veterans.  I imagine Gregor's waking as a transformed creature to parallel the waking of a veteran after having lost a limb, for example.  The world would be entirely different...you would have to adapt to your new body.  Like Gregor, many veterans changed in more than physical ways after the war.  They, too, lost their appetites for what had once been their favorite foods, or could no longer bear the sight of their happy childhood belongings.  Shellshock and depression caused these effects in veterans just as Gregor's transformation triggers them in him. They may have felt the same burden of needing to care/provide for their family yet being unable to.  Some may have no longer been able to communicate with them.  Their wounds may have caused others to view them as monsters. Considering Gregor's struggle in adjusting to his body to be that of a veteran makes Metamorphosis a poignant examination of the after-effects of war wounds on both the men who have suffered them and their families.