This oath is well-meaning and would likely serve its major purpose, to make citizens very conscious of their responsibility by creating a duty to serve their oath to preserve the beauty and not besmirch it. Where oaths cause problems is always in the details of what might happen when the oath becomes untenable in some way, incompatible with something that is a greater good, a higher observation, a higher obligation, or a more compelling circumstance that might require going against the oath in service to one’s survival, for example. So we would say that oaths are all well and good, but realistically, there are almost always conceivable circumstances where an oath might have outlived its usefulness and, for all practical purposes, truly needs to be withdrawn. That is something requiring careful consideration if one wants to be true to the self, as well as those for whom the oath is intended to be a beneficiary, after all, what one is stating with an oath is to give something to others no matter what.
One does not typically take an oath to oneself, so it is always an outside party to whom one becomes bound in a formal way through the taking of an oath, and this is why it can be something that backfires, because circumstances change, people themselves can change, and sometimes oaths are obtained under false pretenses where it is not fully clear to the oath taker what they are saying and doing, and its potential consequences to be subverted in some way, to put a person in jeopardy even, and take a risk or consequence they never envisioned might happen that puts them in harm’s way, and so on. So, at a minimum, this suggests one should always look before they leap, even if an oath seems routine and trivial in its requirements, so that taking the oath seems to carry no great liability or risk to the person, but we can tell you from long practical experience in observing the workings of the universe, there are many, many times when oaths backfire.
This very oath could put a person into conflict where something might be needed that others would criticize as taking something away from the beauty of the city but serves a higher purpose in some way, perhaps something of a practical necessity. For example, using some property originally earmarked for a park to provide a needed service that not only adds convenience but might prolong lives in some way. For example, locating a hospital in closer proximity to a population center so emergencies can be better dealt with in a timely fashion, and for the convenience of many infirm or elderly people to visit outpatient clinics and doctors’ offices without having to travel a greater distance that would complicate their lives unduly.
In actuality, life is filled with many challenges to find one’s way to success without making moral compromises. This, indeed, is the purpose of oaths, to predefine an end goal, a guideline for living, to represent a kind of minimum one is agreeing to, to lessen the chance someone might do something self-serving or shortsighted for personal convenience at someone else’s expense, so the oath serves as a kind of fence around them, put in place to limit their choices for a greater good that is stated as a part of the oath, if only in a vague way. The very need for oaths is because humans are unreliable. This tells you all you need to know about the value of oaths to begin with and the likelihood of them being honored without introducing further complications, moral dilemmas, and in some cases inducing a person to make worse choices than even the oath would seem to save them from.