I mean, I agree with you, but the upcoming 2024 books are almost EXACTLY the same kind of thing as Essentials (aside from the fact that that line's main purpose was to give Barnes & Nobles (or whoever "mainstream" store it was) instructions on how to sell D&D for employees who knew nothing about it. (This is why they called it "Essentials" - they were the products that WotC wanted the stores to understand were the important ones to get into the hands of new players).
Except that amongst its express purposes, per statements from the designers like Crawford, is that it will address known and persistent balance problems (like short-rest classes being shortchanged relative to long-rest ones, Warlock and Fighter in particular), to respond to customer feedback fixing both high-level stuff like how the DMG is written and low-level stuff like unpopular classes (e.g. Ranger) and unpopular subclasses (e.g. Berserker).
It's very specifically fixing problems, not just providing an alternative entry point. It
is replacing classes with new versions meant to fix outstanding issues, they just don't want to upset anyone by
saying that they're replacing what came before with something meant to be actually better. Not to mention stuff like the brand-new weapon mastery stuff that the current rules completely lack.
Otherwise, Monsters designed with the benefits of hindsight, ditto for the organization of the DMG, and improved versions of the classes... 2024 Core is the same, design-wise (if not marketing) as Essentials.
Nooooope. Because Essentials subclasses did not replace, and were merely
different from and not improvements upon* their original counterparts. There were, in fact, specific rules in place for how to integrate the two together, so that "O-Fighters" for example could pick up Knight or Slayer powers, and the converse a little bit; Utilities were explicitly common to all members of a class, regardless of what subclass they were written for, so long as the power had a level (this is why they—IMO wrongly—stealth-errata'd the
Call Celestial Steed power, because originally it was "Paladin 4" and thus non-Cavalier Paladins could pick it up at level 6, 10, etc.)
You cannot use 5.5e Warlock pacts with 5.0 Warlocks and vice-versa. 5.0 characters do not get any special ability to use the new weapon properties.
*In fact, the community at large often found Essentials classes to be inferior to their "original" counterparts, often specifically because of their efforts to break away from existing patterns. Knight was fine, for instance, and a few were even good (Skald Bard was a solid alternative AIUI, on par with but different from "O-Bard"), but Binder was crap-awful, Bladesinger was an idiotic design from day 1 (seriously, Wizard
Encounter powers as
Dailies?!), Blackguard was weak (mediocre striker feature and poor power design), Vampire was finicky, etc. The closest it got to "we are fixing known problems" was Star pact Hexblade, and even then, regular Star Pact wasn't bad, it was just finicky like Vampire (that is, it had the same optimization ceiling as other Warlocks, but a much higher floor—that is, a mediocre-constructed Star Warlock was weaker than a mediocre Infernal, for example.)
I get why there is a comparison, but the fact is, "2024 5e" is actively trying to replace the original rules with new rules that do a better job, or fix customer complaints, or improve performance. The claims of backwards compatibility are primarily about (a) emphasizing that old adventures and monsters will still work fine, (b) assuring players that the underlying math isn't changing, and (c) pretending that the classes being replaced aren't
actually being replaced...even though the new ones are specifically designed to be better by their chosen metric of better design, "70%+ of players say they like it." Because honestly telling people, "We messed up on some of the classes and subclasses, consistent feedback has shown this, so they needed to be rewritten to work out some of the kinks. Please use the new versions, we promise we've worked to make them the best they can be!" would upset fans who like the current state of affairs. By pretending that the replacement is
merely offering a purely additive equivalent alternative, they can quietly phase out the old books and content without driving anyone away.
Effectively, they're recognizing "we can't take their books away," but countering with "we can quietly discourage the old rules until almost nobody uses them anymore."
So I guess that's where you and I split on this. I see it as extremely obviously and transparently replacements, because they come from
explicitly admitting that players are playing in ways counter to how 5e was designed (e.g. taking too many long rests and
far too few short rests), from explicitly recognizing that several existing classes and subclasses have gotten consistent negative feedback and thus are not up to par, from implicitly recognizing that players in general want certain core rules (backgrounds and races, mostly) to work differently, and from implicitly admitting that certain areas (the DMG generally, the equipment rules, non-combat/downtime activities) have been poorly handled or neglected, and thus replacement is required.
However, WotC believes (rightly or wrongly) that if they take the final step there and admit that this means the new rules really are meant to
replace the old ones, not augment them, it will piss players off and hurt sales. Since explicitly recognized goals cannot be achieved
without replacement—e.g. you cannot fix the explicitly-recognized problem of "Warlocks get shortchanged because folks don't Short Rest often enough" and "LR classes are overpowered because folks long rest at the drop of a hat"—this means they are saying one thing and doing another.
Essentials classes were new, different takes. They weren't replacements. They were designed to be able to integrate with previous content, even within a single char. "2024 5e" doesn't work like that. If you use a 5.0 background as a 5.5e character, you're just shortchanging yourself. If you play a 5.5e Warlock, you literally
can't use the 5.0 Pacts, and the Hexblade Patron is essentially useless because of the changes to Blade Pact. Rangers in general are integrating various efforts to fix public criticism of the class. Berserker, notorious for being so self-sabotaging it wasn't worth playing, has been heavily rewritten, and is just generally better. These are not "totally new take" options that provide something refreshing and different. They
are replacements. WotC just won't call them that, because being frank with their customers might (probably would) cost them sales.
Original 4e was
forwards-compatible with Essentials. 5.0 is not forwards-compatible with 5.5e, in several places. WotC just won't ever say that out loud.
The great lesson of 5.X is: "if you don't tell someone what something is for, they can't get upset about it." Obscurantism is a sales tactic.