Traditionally, S&W put the "MARCAS REGISTRADAS" on it's revolvers to show that it was a genuine S&W and was a trade marked product. This was especially important for the Latin American market where S&W revolvers were constantly in high demand for several generations. Cheap cosmetic copies made in Spain or Belgium flooded the south America and were often promoted as real S&W products.
There is no really good reason for S&W auto pistols to carry these markings except that they are identified with "real" S&W products.