I work regularly on and with game engines at work. But I don't design games professionally (but as a hobby, if that counts for anything).
But are you really going to tell me that you don't see what Bethesda probably wanted to do, but just couldn't or had to work around their tech? It begins with small stuff like pathing errors of enemies and companions when you engage in vertical combat, loading for every zone change, lack of reactivity for actions from both the world and its inhabitants, clunky implementation of mechanics like stealth, outdated hit detection and feedback when it comes to ranged and melee combat, akward or no blending of animations, unstable physics, where objects behave erratically when more complex forces have to be approximated, etc.
The ambition is probably there, at least that's what I got from their marketing, but the game falls flat in every way. And yes, I do think a huge part of that is because they refuse to either fundamentally rework their engine or adopt a new one. Also their solution for how to "explore" planets is clearly a workaround. Their stuff can't handle putting and streaming a lot of geometry over vast distances, probably because of how their object management in a level works, so they decided to procedually generate limited areas around your landing point, that aren't even consistently connected to each other. All this stuff to me looks and feels like they're working their way around their tools and their tech stack.
If they don't and this is really "working as intended", then that's even worse. And Microsoft should start looking at firing Todd and the rest of the management.
And don't get me started on their writing and quest design, which hasn't evolved one bit from Oblivion. They clearly have some sort of quest editor with triggers that designers use but I can still verify these bits and pieces they have used a decaded ago in Starfield. And that's all fine and obvoisly a boon for the quest designers. But it would be cool to experience something that has evolved and where you don't go "huh, this works just like it did in Oblivion."
Look, man. I was an "apologizer" for Bethesda and their engine before Starfield, believing that Starfield is a "testbed" for evolving their core pillars, changing out and evolving major modules of their tech stack, which is why they've chosen to do it in a new IP, rather than using an established IP for that. But nope. Yes, they have updated their renderer with some prettier lighting and 4K textures and that looks nice enough for the most part, but pretty graphics get boring quite fast. Especially when everything else is lacking behind.