No, these functions are absolutely useless and serve no purpose other than to encourage code to be written so it only compiles on Windows.
snprintf is perfectly safe (when implemented correctly) so snprintf_s is pointless. strcat_s will destroy data if the buffer is overflowed (by clearing the concatenated-to string). There are many many other examples of complete ignorance of how things work.
The real useful functions are the BSD strlcpy and strlcat. But both Microsoft and Drepper have rejected these for their own selfish reasons, to the annoyance of C programmers everywhere.
