Being fair here, this game has a specific 'toy box' of mechanics components it tends to use; you don't need to be a gaming prodigy to recognize them and quickly put together how mechanics work, especially if you have done savage content, or any other sort of serious endgame stuff; higher-end content in this game tends to give you a lot of practice at quickly recognizing which "LEGO bricks" are being used to build a specific mechanic and reacting accordingly.
(It's one reason I love fights that bring new or different pieces into play.)
To folks who are used to watching ground AoEs, I've run into many who view a mechanic as a monolithic whole; as a result, a new dungeon is a whole set of new mechanics. Whereas for folks who are used to doing endgame content, most I know -- myself included -- think of mechanics as basically individual building blocks stuck together; that means a new dungeon is generally the same mechanics, just maybe shuffled around.
And I think the difference that mindset makes in terms of how new content lands is a bigger one than it might appear to be at first glance.
Which is why one set of folks can say "It's new content, getting the mechanics wrong a few times is what happens." and another can say "It's just the same old thing we've seen dozens of times." and both can be correct from their respective points of view.
I think the power creep on older content is less by design and more a factor of the fact that this game's level syncing (and ilevel syncing) is... well, it's sure a thing we have, but I'm not sure it's a thing that entirely works. Locking content to the minimum ilevel would prevent some of that power creep, but a lot of people -- and this certainly applies to some savage raiders -- would probably balk at that, because it would make gear progression feel "meaningless".
(No lie, though, I'd love to see the functional ilevel on the Crystal Tower raids cut down significantly, so that mechanics happened again there. Not because the game needs more difficulty overall, per se, but because those ones have gotten to the point where people overpower them so absurdly that quite a few folks I know who think the MSQ difficulty for current content is their preferred level still have their own complaints about how toothless the Crystal Tower raids specifically have become.)