Textual: Mormon is our editor here, a point that should be obvious, but which bears emphasis. As an editor he makes choices about what and how he tell the story he wants to communicate to his audience. In this case he has a story to tell about Noah. Mormon clearly thinks poorly of Noah (as will we by the end of the story). When Mormon tells this story he allows his antipathy to color he way in which material is presented, and these two verses are illustrative of how he crafts his version of the events. Make no mistake, this is Mormon's view of those events, not necessarily the participants view.
In verse 8 Noah embarks on a building spree. He builds many buildings, and decorates the with fine and valuable things. In verse 9 that building continues with the building of Noah's personal palace. Once again finery is noted. What Mormon does is paint the building of the personal palace as a selfish and greedy thing. We can tell by the descriptions and particularly the decorations with precious metals that this is vain and imprudent man.
The historical picture is probably very different. First, let's take a look again at the events of verse 8. Noah goes on a building spree. While Mormon's implication might be that is was through overburdening his people, it was through an imposition of a twenty percent tax on mostly luxury items or trade items (see verse 3 and comments on verse 3). A tax of only twenty percent, and that only on some parts of our production, would be welcome relief to most modern Americans. It sounds bad because Mormon wanted it to sound bad. In comparison to what many modern societies are used to, it might be seen as a bargain.
Of course the real question of such taxation is the use to which the taxes are put. While Mormon manages to focus our attention on the personal palace, a close reading of the text notes that these had to be public buildings, a program of improving the public architecture. Thus much of the building apparently went for public consumption rather than Noah's personal consumption.
The next very important point is found in verse 7: " Yea, and they also became idolatrous, because they were deceived by the vain and flattering words of the king and priests..." Mormon's reporting of this time period again highlights the iniquity of Noah. What it downplay is the apparent willing participation of the people. This was not an oppressed populace taxed against their will to feed the personal benefit of a selfish king, but rather a populace which had accepted the same cultural definitions that their king did (Jackson and Tanner agree that "there is no hint in the record that they saw themselves as oppressed" Jackson, Kent P. and Morgan W. Tanner. "Zeniff and Noah." In: _Studies in Scripture, Volume 7, 1 Nephi to Alma 29. Deseret Book Company. 1987, p. 232). Those definitions described the type society that they were, and the public architecture would proclaim their acceptance of that model of life - a model that bespoke a generalized wealth and prosperity of the people. Because this adoption of a new culture apparently also included the adoption of that new culture's religion, This change of religious allegiance is apparently also supported by the people, but is certainly the cause of Mormon's clearly antipathetic view of Noah and his reign.