You can say that Darby but when they have not been implementing good tells of what the encounter will be doing next or the bad stuff is hiding within a collision box the addons prevent some unfortunate events. I use to only play with baggins and bartender for the longest time and was able to do WoD mythic raiding pretty easily.
I pug raids now, and might just do a few bosses in Mythic, usually clear heroic but I can tell the boss encounters are not well thought out for giving out tells. It is unfortunate, can it be overcome? Sure could, but it could have been downed a while back from AI warning the user on what to do next in the heat of the moment. There is no need for addons at this point in time, Blizz has enough feedback of the usage that they should design with their own UI in mind.