AUCTeX has the LaTeX-environment function (C-c C-e by default) that does even better than that (inserts the figure environment, offers to center, creates a label, a caption, etc.), and also handles all environments, plus there's no need to create the snippets.
I just used figure as an example. If there's no predefined keystroke or function available such as in the case of LaTeX macros that you tend to use frequently, snippets can be of use. Of course one can do without them, but they're definitely worth considering if you use emacs regularly.
