As it relates to the crux of his post -- whether the ascension of Christ is a necessary component for our salvation -- I came across a few verses that seem to speak directly to this point.
27 Wherefore, my beloved brethren, have miracles ceased because Christ hath ascended into heaven, and hath sat down on the right hand of God, to claim of the Father his rights of mercy which he hath upon the children of men?
28 For he hath answered the ends of the law, and he claimeth all those who have faith in him; and they who have faith in him will cleave unto every good thing; wherefore he advocateth the cause of the children of men; and he dwelleth eternally in the heavens. (Moroni 7)
Mormon's words here seen to answer the question pretty directly. Christ's ascension to heaven allows Him to "dwell eternally" and "advocate the cause of the children of men." The act of His atoning sacrifice allows Him to "sit down on the right hand of God" and "claim of the Father his rights of mercy which he hath upon the children of men."
That is profound and beautiful doctrine!