I sometimes write or mention something about which addons to use in different situations in WoW. It is true that most WoW-related sites on the internet covers the use of AddOns to some extent. Yet there are quite varying opinions as to the usefulness, or rather necessity, of using AddOns. Few say you don't need any addons at all to play endgame (you could level decently by only using a standard ui), but opinions differ as to what extent addons are needed, and for what purposes. Debates flame up constantly with one side saying "you don't need that addon to play better" and the other says "oh yes you do". And then there are the addons that simply make life a little more comfy, without making you a better player in the progress. The last category, which could be bag-addons, sell/buy/auction-addons, map-addons and the like, usually only make out of combat parts of WoW a little easier, and as such aren't necessary to improve your playstyle. No one can say you should have had Auctioneer to down that boss.
So what I am interested here is what combat-addons are needed, and why? Or why not?
Like I've mentioned before, combat addons are used for one thing, to tell you stuff you need to know about in an easy way. It's about providing you with as much information as possible. Some addons are also used to aid you with converting that information into a quick reaction. This is something I will talk more about when writing about good addons for healing.
This means combat addons do two things; provide information and provide a way for fast reaction. For example you can have an addon that shows you who has a certain debuff and another addon that helps you dispel that debuff fast (or one addon to do both of those of course).
If we start by looking at the information bit we can see that every addon get their information from WoW itself. Blizzard doesn't hide necessary information, like who gets a debuff, who is hurt, how far away is someone and such. Technically, all this information is already in the game, and you don't need an addon to see it. You might however need an addon to see it in the way you want to.
The problem with the Blizzard ui (in my opinion) is that it's extremely rigid. You can't move anything to suit your playstyle. It takes way more space than it has to. Also it is designed to work for any class in any spec, and therefore doesn't work especially well for any. It can provide general information, such as how much damage you do to a certain target but that's basically it. Now correct me if I'm wrong, for I haven't used regular Blizzard ui for many months... or years perhaps. They do add new features all the time, features who usually are the most used addons. Like an addon to show you where to go to do your quests and aid with the switching of gears.
If you want information about when to use a certain skill presented in an effective way you'll probably have to use an addon (effective is quite subjective though). Want to know if your trinket is ready to use again? Want to know if your 3 min cd is ready to use again? Want to know how long time it is left before the boss does his certain doom attack? Want to tell people you've used a certain spell? All of the above can be seen or done in WoW, but not in a practical way. You could macro all your spells to announce when you use them (or at least the spells you want to announce). Or you could get an addon that does all this for you. Saves some time, and is usually alot easier to turn on/off or do changes to.
And these are the key words here - "saves time". Out of combat this doesn't matter much of course, what you do while standing around is up to you. But when things get hot and heavy, you want to know stuff as fast and clear as possible. You don't want to have to dig around in drop down menus and whatnot to know what you should do next.
All the addons I have, I've gotten because I thought I could do something better. I got myself a new ui because I didn't like that I had to move my field of vision to the corners of the screen to see certain information (like how much rage I've got on my warrior). I prefer my information as close to where I usually look as possible. When tanking I want to look at the mobs. Everything that forces me to look away from the mobs annoys me. I don't want to have to scan through the combat log to know what happened to who when fighting. But the information is there (just not where I want it), and if you're happy with the way it's presented in the Blizzard ui, I don't think you need an extra addon for it.
So next, the addons that help you with a fast reaction. This goes hand in hand with the information addons of course. Like I said, the Blizzard ui will tell you who has a certain debuff (since you can see their debuff icon). This means however that you have to scan through every persons debuff and then successfully identify the one you need to remove. If you can do this really fast, you don't need an addon for it. And by really fast I mean within a gcd fast. If you can't do this within a gcd, or without keeping your attention from everything else you have to do, you need an addon to help you.
Some addons help you cast spells faster, like Clique. It allows you to cast a spell on someone with having to target them first, which greatly increases your reaction time. I think however that this could be accomplished with some nifty mouse-over macros, so you don't need clique to do this in the game either.
So what am I really saying here? Something quite obvious. Addons don't actually add anything to the game, that would be illegal. They take something from the game, and present it in another way than Blizzard does. Except for the estetic part, there is nothing an addon does that you can't already do in the regular Blizzard ui. This means that if you're satisfied with the estetic part - you don't need addons. Big note however - I don't know of anyone who hasn't gained (i.e become better player) from using at least some addons. The way the information is presented in WoW just isn't efficient enough for 99,5% of the WoW population.