While many would consider it obvious to state that the attitude in a poem illustrates the attitude of the poet, it is most appropriate to assign the attitude presented in the poem to the narrator. Readers can, in some instances, illustrate through textual support or research that a poem's narrator is actually the speaker.
In the case of Margaret Atwood's "The City Planners," one cannot be sure that the poem's narrator is Atwood herself. Therefore, the answer to the question will examine the narrator's attitude towards the city planners.
Given the word choice of the speaker (pedantic, sanitary, rebuke, and hysteria), the narrator is very unhappy with the city planners. They have insured, through their planning, that the majority of natural images (the sun, naturally growing trees, and snow) are over-managed and (in some cases) obliterated from view all together.
Essentially, the speaker despises the city planners because they have insured they have complete and utter control over all aspects of the area. They have gone so far as to even remove all aspects of naturally occurring nature.