It would be complicated for a large base, and too simple for a small one. First, you have to go and get the ton of materials for your large city with a dome. It might be easier than building it by scratch, but imagine the complications of placing it on the surface of the Moon without it looking strange from the uneven surface? Also, it would take up a ton of space, destroy incredible amounts of blocks, and take forever to build.
Then for your small base, it'd cost more for the base block than it would to just place the 20 blocks for a base.
Then for your small base, it'd cost more for the base block than it would to just place the 20 blocks for a base.