The assignment of positive and negative charges to particles in physics is not based on arbitrary guesses or "good" or "bad" choices. The convention of assigning the electron a negative charge and the proton a positive charge was established before the nature of charge was fully understood. The historical choice of sign convention for charge is based on the observation of the interaction between charges and the direction of electric currents.
When early experiments were conducted to investigate electrical phenomena, it was observed that certain objects could attract or repel each other. Benjamin Franklin, an American polymath, proposed a convention for electrical charge in the 18th century. He called the charge gained by rubbing amber with fur as "resinous" or negative charge, and the charge acquired by rubbing glass with silk as "vitreous" or positive charge. This convention has been followed ever since.
Later, with the development of a deeper understanding of electromagnetism, it was discovered that electric charges are associated with the exchange of particles called gauge bosons, such as photons. The theory that describes these interactions is known as quantum electrodynamics (QED).
In QED, the sign of the electric charge is related to the behavior of particles under the electromagnetic force. The choice of the sign convention for charges is consistent with the observed behavior of particles and the mathematical framework of the theory.
Changing the sign convention for charge would require redefining the entire framework of electromagnetism and developing a new consistent theory that can explain all the observed phenomena. It would also involve revisiting and modifying countless experiments, equations, and theories that rely on the current charge convention.
While it is always possible that new discoveries or developments in physics could lead to a deeper understanding of the nature of charge, the current convention has been extensively tested and confirmed through numerous experiments and theoretical calculations. Scientists work within the established framework to build upon existing knowledge rather than arbitrarily changing conventions.