I have been thinking a lot lately about conversion, and I have come to realize that a true and full conversion includes the whole soul - both body and spirit. If someone is not converted spiritually AND socially, that conversion is not complete. Joseph Smith preached community/kingdom building far more than "personal" salvation. In other words, a full conversion is spiritually (individually) to the Gospel and physically (socially, collectively) to the Church - carrying a personal understanding of the theology and doctrines, but literally losing social individuality within the greater unity of the Body of Christ.
In this light, I think ordinances strengthen both aspects of full conversion - the individual and the communal, the spiritual and the physical. They teach and reinforce the Gospel, usually in symbolic ways that can bring continued understanding of Gospel nuances, but they also tighten communal bonds as they are shared - as our eyes behold others participating with us. Lastly, they provide an actual, tangible experience that I believe becomes embedded into the very archives of our soul. That last point is as true of the sacrament (renewed baptism) as it is of the temple.