I love how the purists call people who use mods "bad". They essentially want a game where content is easy to the point where things are merely tank and spank fights.

If you give the community an option, they will use it to help improve their performance. Is it needed? Nope. Will it help? most definitely. You can be the purist who runs completely with no addons or customization. If you're still able to get through content, then good for you. Although I highly doubt that many of the "purists" are on the bleeding edge of content.

*Edit* Trust me, there are thousands of people in WoW and the like who use mods and still fail on a regular basis. They aren't an instant win button