How does the frost use ambiguity to present his message about walls and neighbors?

Robert's poem gives the reader the understanding that the wall in question is a good thing, but it does not take that very long to see that the speaker actually doesn't care about the wall. The poem's ambiguity lies within the very fact that we cannot really be completely certain if we truly need wall at all or not-do they help us or harms us more? 

The mysterious work is known as Everyman and the play by Christopher Marlowe titled Doctor Faustus are both "profound quality plays" in the least difficult sense, since both endeavor to show moral, Christian lessons. Everyman is a "profound quality play" in the strictest feeling of the term; Doctor Faustus is not, if simply because it was composed for a perpetual open theater.