We can use Siegecrafter Blackfuse as an example, since you like it so much... Out of the 18 abilities listed in the encounter 8 can or will deal damage to multiple opponents if you get hit. That is approximately 44% of all abilities. On Mimiron encounter the three parts of the boss has 3 shared abilities and on top of that 7 abilities unique to one of the thirds only. Out of those three shared abilities one is a dummy used for the encounter design (heal if not all parts die at the same time, since players can never be in parts I think we can discount this as a possibility for players to ever get). Out of those 7 other abilities 6 deal AOE damage either around the boss or around the target. That's 6 abilities out of 9 or 66% of Mimiron encounter is random AOE.
Now please, with simple yes/no answers:
1) Am I right when I said most of the tech abilities done by NPCs currently in game are AOE damage?
2) Would a class that has same kind of ability breakup as current NPCs in game be good design as you claimed?