A world without difficulties is a world without champions.
I don’t mean to trivialize suffering, or to give a trite answer, but think about it. If there was nothing to overcome, there wouldn’t be anyone who had overcome. We’d lack champions and heroes. Our stories would lack conflict, and conflict resolved. Victory would be a word without meaning. Perhaps in suffering, God allows humans to foreshadow, in their own small victories, that Great Victory that will be His alone, already begun, but yet to come.