I think many arguments against such an idea of dreams as the afterlife, are based on weakness of the human body or with God as not being perfect. I believe we simply will never know, while living, who this God or Creator actually is, and perhaps not even after we die. Man decided to believe in a perfect God, but what if we were to start believing that whoever the creator is, they or he is not perfect, and neither is his creations.
I think all religions are basically good. They all teach goodness as the ultimate goal. If we could say that dreams are not themselves heaven or hell, but only give us a view of what lies ahead, then we might be able to better accept the weakness of this theory. Some people cannot choose to be good or bad because of some defect or illness. Science can manipulate dreams and probably can even prevent them. But we are talking about the physical body which is needed to have the dreams. This same body that is needed to house our souls. Many believe the soul will live on regardless, so why not the dream? Perhaps the only dream a person ever has may be when in the embryo, but that may be enough or even less may be enough. I suspect the first 9 months of life is still pleasurable and the unborn child does dream.