The usual remark that goes about in a first encounter of Dirac monopoles is that it solves the problem of electric charge quantization. I have also studied t'Hooft Polyakov monopoles which asymptotically quantize the charge. Basically they prove that $ e g \in k\mathbb Z$ where $k$ is a dimensionless number, $e$ is the electric charge and $g$ is the magnetic charge.
First of all, what do we mean by saying that charge should be quantized? Are we trying to say that all electrical charges we find in nature are integer multiples of the electronic charge ($e=1.6\times10^{-19}C$)? In that case, isn't the obvious explanation the fact that everything is made up of electrons and protons? Why take the trouble to invent monopoles to explain this matter of fact?
Perhaps we are trying to explain why the electronic charge is that particular number. Surely, the $U(1)$ charge can be any real number. But I do not see how quantization of the electrical charge helps in explaining this number anyway. Instead, it raises more questions. If $U(1)$ charge is quantized, which is to say that several integral multiples of a charge quantum are allowed to exist, where are all the other elementary particles with all the integral multiple charges that are allowed? How many times the charge quantum is the electronic charge? What particle has the minimum allowed charge? If that particle happens to be the electron (and why is that?), and you are going to explain charges of other composites of electrons in terms of the electronic charge, why bother invent the magnetic monopole machinery in the first place?