No, I understand just fine. But you just succinctly explained why this attack ISN'T a basic attack. It has little in common with a basic attack. It doesn't even fill the same purpose for the class as a basic attack. I see and understand your position, but you're speculating about this power's purpose. It fails as a basic attack. Personally, I would see Weaken Mind more as our "basic" attack.
Weaken Mind fails the "basic attack" test mainly because it's a DoT: chain casting Weaken Mind isn't going to do you any good since you're just refreshing the DoT. A basic attack has to be functional but suboptimal in a vast majority of situations (re: it has to be the last thing on your priority list). Disturbance is just that. It's not optimal for *any* Sage spec. It's the least important ability for any Sage (Seers would rather reapply Weaken Mind and/or use TkT if it's not on CD, but Disturbance is what they use when they have to deal damage and fill in empty GCDs otherwise; for TK, it's explicitly the "basic attack" that is spammed when there is nothing else; Balance simply replaces Disturbance with TkT by removing the CD on TkT) which fits in with how a basic attack would work within the Sage resource paradigm.
It's not *supposed* to match Charged Burst or Charged Bolts just because they have largely identical non-damage attributes (1.5 sec cast time, no CD) because those abilities don't fall within the same resource paradigm. Sages are different and, as such, their abilities are different. The role of a "basic attack" is determined by the intended use of the ability rather than by the abstracts of its actual function: Disturbance is pretty much designed to act as the basic attack for a turret class with a massive resource pool, which is why I say it's the "basic attack" even if it doesn't actually match a basic attack using the nominal traits all other basic attacks share. All of those other basic attacks exist within a largely similar resource paradigm (small-ish resource pool with attacks that consume substantial percentage amounts with similarly substantial percentage regeneration on a per second basis); since Sages exist within a functionally unique resource paradigm (massive resource pool with attacks that consume minute portions of total resource on a percentage basis with miniscule percentage regeneration on a per second basis), their "basic attack" should be similarly unique. Attaching the same assumptions to it that you do to all other basic attacks is simply ignorant of the fundamental differences between Sages and every other AC.