LMAO!!!!
This question has fukk all to do with popularity.
There are loads of MMOs with awesome boss encounters that are not Wow... only wow fanboys dont agree with that fact.
The question is have addons ruined Wow... and the FACT that Wow subs have gone down backs up the answer... yes addons have contributed to ruining Wow.
You see what i did there?
Wows popularity/unpopularity has no reflection on how good or bad other MMOs are... and other MMOs popularity doesnt mean shit to how good or bad their policy on addons is.