Despite the fact that vanilla Minecraft becomes easier to modify with each release, with more command block capabilities, functions, NBT tags, custom recipes and so forth, you have to remember that we're actually (technically) a modded server. The server's game play is modified using Bukkit plugins, rather than the built-in Mojang features, predominantly because we get much better performance with plugins. This is the huge difference between Dogcraft and Hermitcraft, for example.
You will see many features that are great for mini-game builders and adventure map authors with every new release of Minecraft, but cool as they are, the plugin system that we use will continue to be our tool of choice.