Why did God want a Tabernacle to live among Israel (Exodus 25:8)? What is the significance of the Tabernacle built by Moses?
Rav Hirsch writes on that verse (Exodus 25:8 -- page 538 in the Shemos volume of this set), that the message of the Tabernacle is based on that verse: "ועשו לי מקדש ושכנתי בתוכם" -- "make for me a Mikdash, and I will dwell [שכן] in your midst."
He writes that our mission ("ועשו לי מקדש," to build the Mikdash) results in ושכנתי בתוכם (the manifestation of the Shechinah).
[ This is an exact quote, comments in brackets and emphasis in bold are mine (italics belong to Hirsch) ]
...... Mikdash, then, is nothing but the expression of that collective task on whose fulfillment the promised presence of the Shechinah in Israel's midst depends. Thus, the statement ועשו לי מקדש ושכנתי בתוכם contains two concepts whose symbolic expression will be the construction of the Tabernacle and its furnishings. These concepts are מקדש [Mikdash -- Temple] and משכן [Mishkan -- Tabernacle].
Mikdash expresses the totality of the task we are to fulfill towards God; Mishkan expresses the fulfillment of the promises made to use by God in return for our fulfilling that task. ......
The Tabernacle is to be Mikdash, the place of consecration, and Mishkan, the place of God's closeness. The Tabernacle is to be a place where we are to seek and attain our consecration and god's closeness. This consecration and this closeness -- i.e., the mutual covenantal relationship between God and Israel, established through the giving of the Law by God and its acceptance by Israel -- is the context within which the significance of the Tabernacle as a whole and in its parts is to be sought and found.
Throughout the rest of the discussion in the Chumash about the Tabernacle, Rav Hirsch discusses how each piece and facet of the Mishkan has its own symbolism and relevance to the message of the Tabernacle.