We push multiple alpha versions to Curse on an average day, these versions may contain important new features or bug fixes for the bleeding edge raid content... These versions are tagged as alpha, so they will not be downloaded by default. Set your Curse client to update to alpha if you want these latest versions (but they may contain bugs, downloads tagged as "Beta" or "Release" are more stable)
A lot of different types of addons are doing exactly the same thing. For example, Cross Realm Assist was an cross realm addon but in fact it is an LFG addon with its own UI. Serverhop and WQGF were doing exactly the same thing from program logic perspective. Even Badboy as a chat filter addon would filter LFG spamming. The idea behind BlockChinese could actually be used for premade groups as well. There is no point for people to install so many different addons for doing the exactly the same thing. These features should share the same code base and work together.
Often the name modification (or "mod" for short) is used interchangeably with AddOn. More specifically, a mod is a third-party AddOn that alters or enhances some aspect of the game's interface. Mods can perform a wide variety of tasks, including adding new buttons to the screen, altering the built-in player and party frames. In extreme cases, mods completely supplant the standard game's interface, usually offering more advanced functionality.