Were you playing/DMing in the mid 1980s when Unearthed Arcana came out?
If yes, I'd be interested in seeing your comparison between [pre- and post-UA 1e] and [pre- and post-Essentials 4e] in terms of how much each editoon changed on their release.
It's not a comparison I can make myself as I've never looked at Essentials.
I was there for both.
UA bumped up a lot of power options. More spells for casters, weapon specialization, higher level limits, expanded more powerful race options, some powerful new classes (particularly cavalier and barbarian), and human rolls. Thieves were still thieves, although they could be mechanically terrible thief acrobats alongside standard mechanically terrible thieves.

Overall it shifted the game to allow lots of higher powered options. All the underdark races's special abilities and class options really outclass the options for a PH halfling.
Looking back at 0e, which was before my time for playing, it would be similar to original box D&D versus Greyhawk supplement one adding percentile strength, the thief class and more spells.
4e was similar but had some differences too. pre-essentials was tight balance not just between classes and races at equal levels, but in resource management on a daily schedule. The at will, encounter, daily, utility power scheme meant there could be really tight PC to PC balance but also a DM could really anticipate how far a party or an individual could go based on their hp/healing surges/ and AEDU powers. Whether there was one big fight for the day and everyone nova'd, or grinding hall fights against hordes of minions that came in waves, everyone had at will attacks and everyone had roughly equal nova stuff over a day. This was through three PHs full of classes and worked well primal expansion classes and psionic expansion ones and one offs like the sword mage as well as the core fighters and wizards and rogues.
4e Essentials took away the AEDU tight equal power resource management paradigm and gave some new classes more at will and encounter powers while dropping some dailies. This fit a number of people's playing styles better, but threw some DM encounter balance calculations out of whack and you had some people with nova powers while others had consistency in power output, which fit different playstyle preferences, but could be not as balanced depending on the situation.
I personally really like the essentials mechanics innovations, particularly in fighter and paladin defender mechanics being easy to track and remember auras at the table instead of tracking fiddly individual marks on specific targets, and I really liked the increased at will options, I recognize there are tradeoffs for going with design to match different playstyles.
So 4e changed the dynamics of the game, but it was not a raging influx of power the way 1e UA human roll stat generation charts pumped up the power of 1e characters.