Are our loved ones who have died walking the streets of gold and singing in heaven now?
No. Loved ones who have died and are in glory are not now walking the streets of gold or singing hallelujahs, because they are not in a body. The body's redemption is still future; it remains under the curse until the adoption, the redemption of the body.
Les explains that God has never used the human being as just a soul and spirit; His work involves the complete entity of body, soul, and spirit. That is why loved ones who have gone on to be in glory are not walking the streets of gold or singing hallelujahs—they cannot, because they are not in a body. The body has not yet experienced redemption and is still under the curse; people still get sick, get wounded, and die unless the Lord comes. The context therefore points to waiting for the adoption, namely the redemption of the body (Romans 8). Les also says eternity is outside time, so from the perspective of those in glory, the elapsed years are not relevant, and he does not speculate about what they have been doing.
Are departed believers walking the streets of gold and singing hallelujahs in heaven now?
No. Departed believers are not walking streets of gold or singing hallelujahs in heaven now, because they are not in a body. They await the redemption of the body, when the complete entity of body, soul, and spirit is realized, as Scripture teaches.
Why aren't our deceased loved ones in glory walking the streets of gold or singing hallelujahs?
They cannot yet walk streets of gold or sing hallelujahs because they are not in a body. Scripture speaks of waiting for the redemption of the body, not only the soul. God's completed purpose requires body, soul, and spirit together; the body remains under the curse until that redemption occurs.