There are two sides in this issue.
First, it is in the nature of the universe that destroying something is much easier than creating it. That is reflected in Hermetic magic, as we see that permanently creating something requires raw vis while destroying the same thing doesn't. In this way, being able to bring down an Aegis without requiring raw vis is consistent with the nature of the universe. However painful it can be, it is a fact of life.
Second, the economy of the Order of Hermes relies heavily on raw vis. Collectively, maintaining the defenses of covenants through castings of the Aegis is probably one of the big vis expenditures of the Order. As Vortigern mentions, if it is too easy to bring down the Aegis, then it becomes worthless as a defense. Or, if it is easy to do, then there must be a reason why it just isn't done.
By temperament, I tend to be a builder rather than a destroyer, so I would like to make it harder to bring down the Aegis. It is a reflex. But is it the right one?
I don't think it is, at least as far as Hermetic Magic is concerned. Because there are other mechanisms in place in the setting that prevent magi from doig so. By the Code of Hermes, bringing down the Aegis of a covenant falls under "I will not deprive nor attempt to deprive a member of their magical power" clause. It can also fall under "I will not endanger the Order through my actions" clause, if done repeatedly, as it risks the peace and security of multiple members. So I believe that the act of bringing down another covenant's Aegis would be investigated quickly and punished severely. After all, magi would consider that if it is done to one covenant, what is to prevent it from being done to theirs?
How severely would it be punished? A first offense could easily result in a severe fine in raw vis, plus the loss of a familiar, apprentice or some other valuable resource. Repeated offenses would almost certainly result in being cast out of the Order and Marched.
Just knowing such a spell, if one isn't a well-recognized Hoplite, would certainly raise questions. Much more than knowing a Parma-destroying spell, since that can be a legitimate weapon in a Wizard's War. Waging war on a covenant is rarely legitimate without Tribunal sanction.