I believe that the paper gets cited because it was the first to identify a new class of objects, fluxbranes, which are present in most theories of supergravity. As the "low energy" limit of string theories and M-theory (our leading contenders for a fundamental theory) are such supergravities then their existence could play an important role.

The novelty follows from the nature of the solution rather than the technical details of the calculation. Fluxbranes came from getting a physical picture of the system, then using the machinery of supergravity to verify the intuition. The fundamental objects of string, M-theory are charged and so have an associated flux. It is this ubiquitous nature of fluxes which gives fluxbranes their role.

A simple route to understand fluxbranes comes from familiar particles, electrons. When gravity is included then, loosely speaking, the electric flux between an electron and positron will travel along a tube, a flux-tube. If we now replace the electron with the strings, membranes, and p-branes of supergravity we see how a flux-tube should get generalized to a fluxbrane.

The presence of fluxes can do strange things to objects, turning them from one thing into another. It was in trying to understand these effects that led to thinking about fluxbranes.