I've always felt that if 4e had started with essentials that it'd have lasted longer. I much prefer essentials to original 4e.
Well maybe, but it would be less special. 4E stands out and is used even nowadays as inspiration for a lot of games because it did things different and not everyone liked that.
Essentials overall is not bad 4E material, it had some good designs, but the first book was just a punch into the face of people who liked 4E. It went all back to "Simple martials, complex casters", which reflects Mearls taste.
I agree that 4E would have been more successfull if it would have started including some simple classes. And for that part Essentials was also good, to add some simpler classes to the mix, so adding Essentials does improve 4E.
Essentials as itself without the non Essential 4E parts though would just be a worse game lacking lots of the parts making 4E special like the Warlord.
I think the best 4E could have done was to release with the Ranger as the Essential Ranger (Hunter (and maybe also Scout)) to have a 2nd controller as well as the Essential Elementalist Sorcerer. (Instead of the original ranger, and the warlock (which could be later introduced))
This way there would have been 2 simple to play classes, which are quite elegant and work well, without having this stupid limited mindset of "simple martial, complex caster", which some people cant get rid off.
Also the Ranger was just one of, if not the least interesting original class anyway not really using the AEDU structure well, and just doing as many attacks as possible. The essential version is here at least elegant.