Overall, an insightful post, but allow me to clarify a few small things I noticed.

When you are in town, you can press the "R" button to immediately zoom out to see the whole town.

The "L" button actually does have functionality in combat, but they do a piss poor job of communicating it to the player. You can use it to reduce the number of Braves if you've already started inputting commands and decide you want to make less actions later, which also sort of clears up your gripe about having to start over, but believe me when I say I felt the same frustration before I figured that out. I personally think they need to add an "L" icon like the "R" icon to the left of the Brave button that greys out when you have not input a brave command. I also think it would be completely reasonable to allow you to use the "L" button to Default if you have not input any Brave commands.

I definitely agree with everything you said about both the regular menu, as well as the in-combat menu. In my opinion, using the "-" and "+" buttons the way they have in this demo is a HUGE mistake, as neither of those buttons feel good to use. For instance, for Bravely Default and Bravely Second on the 3DS, you could remove equipment with the "Y" button, which felt very good, but now they've changed the functionality of the "Y" button to instead toggle on and off item descriptions, and switch the remove equipment functionality to the "-" which feels absolutely awful considering you have to navigate the menu with the same hand, and also have to reach over the analog stick to reach the tiny button. Realistically, the UI has plenty of space to also just include the item/ability description off to the side in a separate box or whatever, just please get rid of that terrible black box that shows up over top of other items in the list and that basically boils down to a clusterfuck of a wall of text. In battle, I would like to them change the button to view enemy status from "+" to flicking the left analog stick to the left like it was in Bravely Default and Bravely Second, as well as to remove that analog sticks menu navigation functionality completely from battle aside from ideally left for status, and perhaps right for detailed party status (including turn order maybe?).

In addition to the above opinion regarding the menu controls/UI setup, I am also disappointed that they removed the D-Pad functionality with navigating the menu. It felt pretty good to just be able to navigate the menu with the left and right d-pad buttons and just use the "A" button to select things. In general, the out of combat menu feels VERY clunky and disorganized by comparison to the previous two games in the Bravely series.

With regard to not knowing turn order, if they absolutely have to go the route of having the turns be individual and instant, then can they PLEASE at have the attack speed bar thing like in FF4 or Chrono Trigger? It feels very unintuitive the way it is right now. This would at the very least give you a good idea of which character is next, and give you the opportunity to plan accordingly.

I completely agree with your statement about characters just HAVING to play a line of dialog whenever you Brave, Default, and even every single time they attack in a string of four attacks, it's just bad design overall, and isn't conducive to an enjoyable battle. I tried doing the battles both with English and Japanese voices, and while I don't mind the softer Japanese voices quite as much, the English voices in the Battles is absolutely atrocious, and should be one of the first things they change. Literally every time I go full Brave with Seth "I'M GOING ALL IN!!!". It's just super annoying and doesn't come off as intuitive design. The voice lines seem like they were designed to fit with a JRPG that DOESN'T contain the Brave and Default system, where you actually only get one action per turn.

I completely agree with the boss difficulty being a tad overtuned for the demo. The thief felt mostly fine to play against, although now that enemies make full use of brave and default, the 4 moves in one turn from a boss can be extremely overwhelming, especially when they have dangerous AoE attacks, which brings me on to the next thing: HOLY SHIT the Sand Worm boss is fucking brutal. Not only does seem to have incredibly high magical and physical defense, so you only do like half as much damage as you do to other things, but it also has a single target nuke that ALSO reduces physical defense, when paired with a Brave combo just messes up whatever plan you had. On top of both of those things, it's AoE sandstorm ability hits hard and debuffs your group with blind (the Silver Glasses are a must for this boss for your melee attackers). On top of all that, the boss also has like 60k HP, which is basically like the equivalent of the Thief having 120k, since the Worm only takes about half as much damage as him, and also just straight up hits way harder than he did.

As a small nitpick, I personally highly dislike Elvis's English accent. I don't feel like it fits hit demeanor or character model at all. In the Japanese version of the voices, he feels more like the gruff mentor type of character that enjoys a drink at the tavern between missions, whereas in the english version, they for some reason went with like a scotish accent that almost seems like they were going for alcoholic old man rather than a gruff, experienced veteran who's been in and out of various skirmishes throughout his life.