Your assuming, of course, that by precious things he is referring to the gold and silver he just mentioned. But how do you know that there weren’t some other ingredients he considered more precious that were included in Solomon’s temple, but not the one he is describing.
You are making an excuse via an arguement of silence. For starters, since it was built after Solomon's temple (which according to the nephi legend he was familar with) it would have contained precious metals - in fact they were used for key parts of the temple.
Read it again - these items were used for other buildings? And if the list of things that were in abundance just one verse before are not precious, just what "precious" things were lacking in the construction of this temple eagles?
The stuff is here:
The stuff is NOT here.
Who CARES what the ‘temple’ was built of?