I'm using:
https://www.braier.net/wow-addon-updater/downloads.html
works great for both, retail and classic.
And to those who question the use of such addon updaters. You clearly do not play WoW with a lot of addons then. There is no point for going through addon updates like every two days and that for 30-40 addons. What a waste of time this would be, downloading every addon one by one, copy folders etc.
Many Addons, espcially right now for classic WoW have updates with bug fixes every day. I would be more busy updating those manually than playing the game.
And just a little analogy: "it is not required". It is also not required to use your car to drive to work. Or Bus/Train whatever. You can walk.