Similarly, rules in the vinaya are introduced to prevent accidents occure in your mind which are sometimes harmful to oneself or the entire sanga community.
Eating at wrong time
Mendicants, I abstain from eating at night. Doing so, I find that I’m healthy and well, nimble, strong, and living comfortably. You too should abstain from eating at night. Doing so, you’ll find that you’re healthy and well, nimble, strong, and living comfortably.(At Kīṭāgiri)
Here, one should consider why he has to be healthy, nimble, strong and live comfortably. The monastic rule is designed for an ideal society who seeks nibbana, where they have to practice meditation in the day time as well as in the night. To meditate, they should have a mind which is nimble . If someone has eaten too much he feel asleep, his mind is lagging which makes it difficult to be mindful. Also eating afternoon or night makes one’s body to feel heavy which makes sitting meditation difficult. Therefore a person who practice meditation should have a light meal. Having one meal in the morning a day helps him to keep his mind active and strong which facilitates mindfulness meditation.
When we consider the problem with dairy products oil and sugar allowed in the afternoon and night from the vinaya, it is important to see the facts mentioned in the origin of the allowing.
These five medicines, that is to say ghee, fresh butter, oil, honey, molasses, are medicines and are also agreed upon as medicines, and although they serve as nutriment for people yet they cannot be reckoned as substantial food (On five medicines)
These medicines serve as nutriment for people yet they cannot be reckoned as substantial food. They work as nutriment, with a small amount which makes it possible to get rid of hunger yet not feel heavy. This is important to have a nimble and comfortable body and mind to practice meditation. In my opinion there is no point of obeying to this rule since one does not practice meditation or mindfulness unless he wants to have orher benifits such as being healthy.
Monks use metal (iron) bawls as well as clay bawls. If a clay bawl i splaced close to the edge of the table it may fall and break apart, as you said a metal bawl would not break into pieces however, the paint can be cracked and the bawl can be damaged. As the process that used to paint bawls with roasted oil is difficult and time consuming, a monk must try to avoid damahes as much as possible. Indirectly almost al the small rules (sekiya) helps a monk to be mindful in day-to-day life and helps to be a thoughtful (sampajānakāri) monk.
One should read origins of each of these rules before judging them.