Tanks aren't exactly bad; they're being made obsolete.
I see a few reasons why
- Too much healing
- "Burst" tankiness; champions and builds meant to survive large amounts of damage in a short period of time instead of constant survivability
- The increasing amount of "outplayable" damage
- The increasing number of champions and items that can "outplay" damage.
The power of these strategies in the current meta is allowing other classes to emulate a tank's job while also doing jobs can't do. Why even play a champion that is meant to soak up damage when you can play a champion that can avoid, undo, or block damage entirely while also being able to do other things? Secondly, the combination of the first two things allow champions to do one of two things: drain tank their way through being focused, or just play around surviving long enough to get in and out of one fight and then go heal up to repeat the process when the cooldowns come back.
