Ever since the connection that God had with man was severed in The Garden, God has been making advances toward full restoration. Bethel, Sinai, Shiloh, Jerusalem; the tabernacles, the temples, the incarnation of His Son... all point to the same thing. God desires to grace us with His presence. He knows that we need Him... and He wants us.
God's plan commenced with a freewill love offering. The people had been given extravagant valuables as they had exited Egypt only a few months before this. Why? Just so they could be rich? No (Jeremiah 7:10 & Ephesians 4:28). God gave them precious possessions so that they could worship Him with them. He wanted them to give voluntarily and joyfully, not out of fear or coercion (II Corinthians 9:37).
The items that were to be crafted from these gifts were these: the ephod (a transliterated word for the garment to be worn by the high priest), the breastplate of the high priest, the sanctuary (tabernacle), the Ark of the Covenant, the mercy seat, the cherubim, the showbread table, the sacred dishes, the seven candle candlestick and its implements.
Why? Why all of the details and demands? That's easy... Exodus 25:8 & 22 declare the reason behind all of this. God was coming to live with the nation. He was coming to meet them and to commune with them. Being their Creator, Redeemer, King and God... He had a right to design the setting. And, He had a desire to design a setting that would help them to understand the gravity and grandeur of the occasion.