Loved your history, Otaku.
I can not just forget Haymaker and Slowking/Sneasel. hah!
I like how BREAK pokémon revived the 1 prize strong cards (level X, primes), but pace was already too fast for most high stage cards (they were effectively stage 2-3 cards).
In my opinion, stage 2 gameplay is WAY funnier than fast elixir + basic/stage1 drawing cards and wrecking havoc around, because complexity of abilities and attacks of those 'mons are really nice to play!
And I think we agree in almost every single part of your text, the problem is not the lack of power, but extremely fast pacing. If you look at the most powerful card today (buzzwole, imo), it doesnt have the biggest HP (although it has 190, which is only 40 lower than Gardy's, lol), doesnt hit the hardest, heck, it doesnt even has the best GX. But, this guy can start causing damage in a incredible fast way, which leaves strong stage 2s vulnerable in their weakest point. So, the thing is: current meta favors speedy hitters, while decreases utility of big cards' basic formes.
IDK why pokemon company did this (let's not bring the money/profit discussion by now), but 1 year ago we had metagross, gardevoir and some others, now the meta is COMPLETELY CHANGED, to the point that a dusk mane necrozma is a better card than metagrossGX in almost all ways (IMO, IMO, IMO).
The main point is: Fast pacing + super basics/stage 1s is what makes the Stage 2s simply not worth it. A stage 2's basic stage (ralts, gible, froakie, for example) has a tremendous utility gap to the Basic anabolized GXs we have. And even when you manage to succesfully evolve it, after a hard task that involves giving prizes, resource loss and turn loss, they are at ALMOST the same power level. For a sake of comparison, some basics have 190HP, 160+dmg attacks and the F***ng Zoroark GX is a stage 1 with 210 HP (as is golisopod too) with broken ability. Greninja and Gardevoir both have 230HP. Greninja's GX is worse than Entei's, and it's ability is the same as a non GX bat(s).
---In ex's era, strong basics were 90-110hp, with some rare 120 ones. Normal basics stayed at 40-60 (same as today, wtf?); Common stage 2 were not higher than 120 (same as highest strong basic exs), while Stage 2 ex 'mons were sitting around 140-160 (almost 50% higher than average for basic ex)!!! Can you se the difference when we compare to nowadays cards? They were worth playing, as the basic exs were too!---
The new collection is givin us Salamence GX and Dragonite GX, they both seems to be great cards overall, but i'm afraid of the insane power creep Ultra Necrozma brought and the new Rayquaza, who promises somewhat solid 200+dmg in T2-3