In Vanilla and BC, raid encounters became too easy when people began using add-ons like DBM. So what Blizzard did, starting in WoTLK and really ramping up in Cata was design the raids around people using add-ons. EVERYONE has equal access to them. People not wanting to download them are the same as people who refuse to use macros. They don't think they should have to put in equal effort that other players do. Not every class has to use add-ons, healers have to use a healing add-on to pull their weight with healing. It is simply not efficient to manually click on a target frame, then press a button instead of healing as you target them.
Your issue about decursing, again, decursive has been around for ages and fights have been designed around it, starting with that guy in 70 Naxx who spammed curses.
The game is not broken just because they started designing the game around the use of add-ons. This is how a healthy MMO that is PC only SHOULD grow. Blizzard feels it is fine, and so do the majority of players. Blizzard killed one add-on in WoTLK that allowed people to draw on the screen and anyone who had that add-on would be able to see it. People were using it to mark the ground with designs to show people where to stand in certain phases. Blizzard broke it because it stopped players from having to think. All they had to do was move to the area someone drew on.
DBM is really made too big of a deal. It doesn't show every ability, it doesn't say there is fire under you unless it's an actual boss ability and he's casting it on a certain person. It says who out of your entire raid got grabbed by the boss and is unable to do anything. Something that can be viewed from the chat log (though the combat log scrolls excruciatingly fast, so there's no way people are going to reliably catch it), just like every other ability it warns of. It's the same thing as people saying, "Tiamat is about to fly in 10 seconds," in XI. Did that make the fight easier to have people aware? No, but it's useful information to know whether you should start resting. Same in WoW, it's useful to know moves like that to know that if you're a melee with no range, you shouldn't go off and pop your CDs only to waste them after 2 seconds when the raid boss becomes immune to your melee.




