OK. Give me all the saving throws of a first level fighter. And all the skills of a first level thief. Without cracking a book. And then tell me how to do spells
You say that in jest but I could literally almost dictate word for word the content of the 1e PHB from memory, lol. There are a few of those numbers I'm not 100% sure about, BUT I HAVEN'T PLAYED 1e IN 20 YEARS at this point and I can still write up a character sheet pretty much from memory. It was a LOT simpler. Thieves have from memory Pick Pockets, Open Locks, Remove Traps, Hide in Shadows, Move Silently, and Climb Walls. Level 1 fighter hits AC 9 on an 11 (well, actually all classes do at level 1 they're all the same). I can go on. Back when that was our primary system I absolutely could give you the numbers for all classes at all levels for all that stuff. I could give you MU's chance to know spell and min/max spells known values for every INT score as well. % spell failure and bonus spells for clerics by INT, all the ability score mods for all scores, etc. It really wasn't that hard. I can still probably tell you the stats for every weapon and armor type and most magic items as well.
I've done it in under 10 minutes including loading the character builder for a class I didn't know. And my Bravura Warlord worked out pretty well
Sure, you can click on "take the defaults", make a few selections that doesn't cover and switch a power around, you won't be figuring out your character's best choices based on desired feat and power progression, etc. I mean basically you have a pre-gen. I could have done THAT in 30 seconds in 1e sans the time it actually took to put the pencil to the paper. Heck, I wrote my own "CB" for 1e/2e that we used for years, it was maybe 1000 lines of code, total. Most of that was laying out the printout and a crapload of static data tables that listed different options for spells, equipment, etc. I am relatively certain the equivalent code in the 4e CB is around 100x bigger than that.
I call it broadening the appeal

I've no objection to the Slayer as long as they don't take away my fighters and barbarians.
Absolutely! Not all the changes in 4e were good ones - just most of them
I'm not bashing 4e at all, but I think that they came up with a great core design and then they messed up in a few relatively small areas. Unfortunately those areas have a big impact on the appeal of the game.
There are simply WAY too many feats and powers in 4e. They should have been MUCH more careful about minimizing the numbers of slight variations of things and designing each one so it had maximum utility for the most use cases vs making 10 very similar things. Powers should have stuck with a much smaller set of variations of buffs and debuffs and such and been more individually distinct. MANY less things should have required ongoing tracking and relied instead on instantaneous effects more heavily.
Honestly, if you look at Essentials in isolation from the grandfathered in support for existing 4e feats and powers what you see is the designers have figured a lot of this out. There are less hair splittingly small different variations of powers and feats. Choices are both more distinctive and less in number. Fewer things require tracking and more of the effects that do last use the existing conditions vs the wild miscellany of buffs and debuffs of pre-Essentials powers. It is just a TIGHTER and better thought out implementation of game elements on top of the same basic core.
There are some things I don't especially like seeing being 'deprecated' like rituals and some of the more interesting leader classes like Warlord, but I really think the devs have CORRECTLY concluded that things were getting a bit out of control and it wasn't really adding a lot to the play experience.
Take magic items. 4e has a metric crapton of items. It has 10x as many of them as 1e or 2e ever dreamed of having. Yet somehow there is little real meaningful variation in a lot of categories. I'd expect Essentials to present only perhaps 100 items or less in total. I bet that 100 items will be more interesting, distinctive, and useful than the 1000's that exist in pre-Essentials.
I mean, it is great to have options of all kinds. The problem is at a certain point option bloat just kills your system for the players. Nobody can really comprehend all of what is available now in CB and no group in 100 years of play could even come close to using the vast majority of it. THAT more than any other thing IMHO is the reason for the existence of Essentials. It is a great idea. Put out a bounded subset of the system that will never grow out of control because it is always just basically 5 small books. Most groups never need more. They will be happy with that. They can tell CB to ignore everything except Essentials and play a good solid interesting game that has replay potential for years. The rest of us that like say Warlord or Rituals can play with the new stuff and the old stuff. I think the whole "it's retro" thing is at best a very minor aspect of the whole thing. They may play it up for marketing reasons but it just really isn't the major driving force behind Essentials.