Hmmm what would be the point of having flesh and blood if there is no need of it? Not saying you're right or wrong just curious if the new body is perfect there wouldn't be need for a stomach,heart,blood,etc.
Because the physical is good. Because the world is redeemed, not destroyed.
In actual, real Christian theology, the world isn't evil. The physical isn't evil. It is good. Gnosticism, Docetism, Manicheanism, etc, were all condemned as heretical because they rejected this.
Jesus is the Incarnation of God the Son. Why would Jesus incarnate as part of creation only to have it destroyed? No; He incarnated so as to redeem.
And Jesus remains Incarnate. He is at the right hand of God the Father with His material body, with all parts normal to it: organs, hair, skin, bone, sinew, muscle, lymph, vessel, cartilage, neuron...the whole package. The Holy Bible tells us this in Acts.
If there is a physical resurrection of the dead, as orthodox, historically-minded Christians are required to believe, then we are so completely. If God created it, it is good, and Jesus Christ was born, lived, suffered, died, descended, was raised, and ascended to redeem that creation.