I agree to a certain extent. I don't think 4e really comes into its own before a GM applies post-Monster Manual 3 math and gives defenses + expertise feats out for free. It works, more or less, but requires the GM to be cued in more than what they would get from just reading the GM guides (which are mostly excellent).

I can see where you're coming from, but consider this: When it comes to games that have an emphasis on combat (and dnd certainly qualifies), it can be useful for GMs to think of their encounter XP budget as their narrative budget. In other words, the more dramatic a fight is, the more difficult it ought to be. Also, inside that encounter, the monsters that eat up most of your encounter's XP budget deserve the most narrative spotlight.

Imagine a GM has been running for a group for some time. Now, a climactic fight is upon them. By all rights, this should be a narratively momentous occasion for the table. Only it isn't. The system's encounter design fails and the whole fight gets completely trivialized. But such is dnd and every once in a while, your planned encounters just end up falling on their faces.

And we accept this. Because that's just how it's always been, right?

Only imagine this happening in another system. What if the gang was playing a forged in the dark system instead of dnd. The situation in the fiction is dramatic and challenging. The GM rightfully calls for many risky and desperate rolls and judiciously applies standard and limited effect. The party should be in for a world of hurt. Except now their dice pools all of a sudden are tripled because the system somehow breaks. In fiction-first games like FitD, this would be unforgivable. The table would be correct to just ignore the core resolution mechanics here because they fail to represent the fiction at play.

But that's exactly what happens with dnd on a regular basis. And it doesn't have to be that way. Encounter balancing in pf2e and dnd 4e (with asterisks) works rather well.

But why should we care to have balance? Oh, tons of reasons. Just the example I've raised here is that balanced combat allows GMs to set out challenges for the party that match the fiction well. This is notably different from having every encounter be equally challenging. Just that they roughly match what the GM had envisioned. And there are lots and lots more reasons.

This isn't to say that balanced combat is superior to swingy, unpredictable combat. Both can be lots of fun. The key is to understand the type of game the table wants to play and lean towards that direction.

Have you looked into Strike! RPG? Setting agnostic tactical combat on a grid heavily derived from dnd 4e but with all the fat stripped, leaving a very light, low-math, simple to run combat with a ton of depth but low number crunching. All that is paired with a narrative system that's very intentionally kept light and with intent to get out of your way.

If you're looking to run something where the PCs are a crew of specialists with distinct roles, this might be worth considering.

Sure thing. Lets say we've got a player who is playing a priest. They have a character aspect: "Priest with six guns. On a mission from God." One of the foundational things about Fate is that a character is more likely to succeed to more involved that character's fiction is in whatever they are attempting to do, but the book doesn't do a good job laying this out to the reader. The players look at their sheets. They see a number of listed actions and approaches. Feeling a little lost, they say "Can I attack in a flashy way?" I think we can both agree that this kind of classic "Mother may I" just isn't interesting during play. We want our players to embrace the fiction and act in accordance with established aspects. But the above is fine, right? It's just the players feeling a little lost and generally being new, right?

I'd be ok with the above if that's where it ended for me. However, during play, I often felt like players would want to involve aspects (as they should). So they'll ask things like: "I would like to try to shoot the chandelier that's swinging on the ceiling down, hitting General Holtz and his men. I'm a priest with six guns. Do you think that this is ok? Oh, and I know it's swinging because Otto just used it to swing from one balcony to another, so could I use the Swinging aspect here somehow? Maybe God could come into picture here somehow." And now you've got to have a full conversation about the act of shooting down a chandelier whereas in other systems you could have just called for an attack roll against object AC with a harness value based on metal or something.

This is kinda what I mean by asking permission. There is a need to have a constant, evolving conversation about the fiction to make sure everyone understands what is happening. When there's uncertainty, the players default to asking clarifying questions and mostly ask permission to do things. I have personally found the need to constantly update this conversation to be a little annoying.

I ran FAE for maybe 6 sessions before throwing in the towel. The system is good, but I feel like it just doesn't have enough game to satisfy me on a personal level. The feel of running FAE is more collaborative story time than playing a game together. This is a feature and a bug of the game. How much it bothers you is very subjective. What I found to be the case with FAE is that my players defaulted to asking permission to do anything out of unfamiliarity and discomfort. After they got their footing and were able to move past this point, they still wanted to engage in discussions about the fiction for extended periods of time. To me, this lowered my enjoyment of the sessions a lot. For such a rules light system, we sure ended up talking about rules and what was possible a lot.

There's nothing in Blades that requires you to run it in Doskvol, but that setting does have a few things going for it that makes Blades easier to run. Firstly, the players can't just nope out of the city and lie low for a while in the countryside. They're forced to deal with Doskvol all the time. Secondly, there are real and immediate consequences to murder and death. This incentivizes the players to at least attempt non-lethal methods. Of these, only the pressure cooker environment is really crucial for a game of Blades. The rest of the setting adapts just fine. You could, for example, run Blades in a post-nuclear war 1950s era New Orleans where the surrounding lands are surrounded by nuclear fallout. The city, however, survives due to protections conferred by devils.

Doskvol is just a tad too dark for Arcane, I do agree there. You don't necessarily have to adapt Blades itself tho. Have you taken a look at a|state RPG? It also uses the Forged in the Dark engine but is a little more lighthearted. In that game, the crew are troublemakers trying to make one corner of a hellish urban landscape into a better place. The system makes caring as important as fighting. I think you might have better success with that system.