What I hadn't noticed before, was that the Book of Mormon contains two other references to spacious buildings outside of Lehi's and Nephi's visions. In Mosiah 11:8
And it came to pass that king Noah built many elegant and spacious buildings
In Ether 10:5
And it came to pass that Riplakish did not do that which was right in the sight of the Lord, for he did have many wives and concubines, and did lay that upon men’s shoulders which was grievous to be borne; yea, he did tax them with heavy taxes; and with the taxes he did build many spacious buildings.
It is interesting to note how the description of king Noah, his priests and his people include words like "pride" and "vain", the same words used to describe the symbolism of the great and spacious building which Lehi and Nephi saw. For instance:
"...lifted up in the pride of their hearts" (Mosiah 11:5)
"...deceived by the vain and flattering words of the king" (Mosiah 11:7)
In his abridgment, Mormon probably notes that king Noah represents the essence of the spacious building symbolism. When he writes that king Noah built spacious buildings, my guess is that he does so with Lehi's dream and the associated symbolism in mind. King Noah becomes the constructor of a vain and prideful people, by erecting the same kind of building that Lehi and Nephi saw.
What about Riplakisk in Ether, who also constructed spacious buildings? We don't know much about him because his birth is described in Ether 10:4 and his death in Ether 10:8. But interestingly, what we do know very much resembles the descriptions of king Noah.
- Noah "did not keep the commandments of God" (Mosiah 11:2) and Riplakish "did not do that which was right in the sight of the Lord" (Ether 10:5)
- They both had "many wives and concubines" (Mosiah 11:2 and Ether 10:5)
- They taxed their people with heavy taxes to finance their lifestyles (Mosiah 11:3-4, 8, 13 and Ether 10:5)
- Noah built himself a throne ornamented with precious things (Mosiah 11:9) and Riplakish "did erect him an exceedingly beautiful throne" (Ether 10:6)
It seems that both Mormon, who abridged the king Noah story, and Moroni, who abridged the Riplakish story and was familiar with the king Noah story, made a pun with Lehi's dream and the spacious building symbolism in mind.
Another interesting point: Evidence is pointing towards Joseph Smith dictating the Book of Mormon starting with Mosiah. It would be incredibly smart of him to include these two subtle details from Mosiah and Ether before placing them in the context given by Lehi's dream with the spacious building and symbolism. Of course, I believe it was rather Mormon and Moroni who did this after knowing about Lehi's dream and Joseph Smith was given their words by the gift and power of God.