Remathilis
Legend
I agree with some of this.
5e casters still have at-will and encounter powers. Plus there is a ritual system for decoupling utility effects from combat prowess. So I don't think that 5e departs as far from "ADEU" as you seem to.
On bounded or unbounded accuracy, I think that 5e is very close to 4e. Just take out the half-per-level bonus from 4e and you get bounded accuracy (or, to put it another way, 4e is built on bounded accuracy provided that the advice in the DMG on level-appropriate encounter building is followed).
The change in this respect from 4e to 5e has knock-on consequences for monster design. 5e at least ostensibly doesn't need minions or solos, though the actual play reports I've seen seem to imply that action economy - which solos are meant to address - remains a big issue, and legendary actions are, in effect, a solution to the solo action economy problem which is more "dissociated" - ie metagame - than anything I can think of in 4e, being nothing but fate points for monsters.
I agree that 5e differs from 4e in certain key elements of action resolution (including combat, especially the action economy, and healing). I was referring primarily to PC builds in my earlier remarks.
I think the return to spell slots (even in its modified form) and the non-siloing of utility/ritual effects (returning all magic into spells, rather than breaking it up over 5 types of powers) is a big factor. As is damage scaling (casting for greater effect) over replacing powers with leveled-up variants after certain levels. Sure, at-wills (cantrips) and some elements of encounter powers (since short rests don't occur after every combat, 5e's short-rest powers are more akin X/day powers) for certain classes, but overall the marriage of ADEU elements (without the strict hard wiring of 4e's frame) to the classic Vancian spell slots is huge.
Similarly, while 4e and 5e might end up in similar places as far as hit ratios in combat, the lack of +1/2 level and not requiring multiple versions (low, med, high) of the same monster is a giant help. I can see the point on legendary though.
Essentials certainly informed 5e's decisions, no doubt. My point is that 4e would have been much more successful if had looked like Essentials (IE familiar to older players) than the rather radical departure it took in the PHB.