Easier or harder than just, like, shoving some one, especially if they aren't prepared for it?
Easier, actually. The most you can do is grasp the seat between your thighs, and the seat creates an absolute limit to how low you can move your center of mass; you can't plant your feet, widen your stance, and hunker down. The best you can actually do is sit up and lean in.
This is why wheelchairs in the real world have cambered wheels, even if the angle of camber is so slight it may not be readily apparent.
I fear you misunderstand me. I'm saying that it was given those resistances to mechanically represent the fact that as a low to the ground mount that would logically be resistant to something like being knocked prone. And even so, I acknowledged that the incarnation you cited went overboard on the mechanics.
You mentioned it as a weakness, I pointed out it has mechanics
specifically to counter that which means it isn't a weakness at all.
Bluntly, your focus feels like it misses the point. You're looking at this and thinking long distance travel, which is not the subject of discussion. I'm looking at this and seeing that you have hours of being Peter Pan every day and thinking of the practical implications of that, not about your ability to travel from Neverwinter to Waterdeep.
Yes, long distance travel very much is part of the topic. D&D has
three pillars of play: combat, social interaction, and
exploration. Overland travel is indeed part of the exploration pillar, and the only time in which long-duration flight significantly impacts play, is during play involving
that pillar. This is a point you, yourself, cannot avoid in your own examples:
...If the paladin is told that the princess's prison tower is on the other side of the fire swamp, she can just fly over the damn swamp and up to the lady's window...
Now the question is, if the DM knows PC's are capable of flight, why did they plan and design a "fire swamp" and a bunch of encounters for it in the first place. At least, encounters that don't involve flying monsters, or monsters with ranged attacks, anyhow. Instead of, you know, designing the
destination with consideration of how one might actually assault it in a fantasy setting replete with
magic, including magical
flight.
That's not redesigning the entire campaign to accommodate flight, that's making a stupid-ass campaign you didn't really think through in the first place. Like I said, it's exactly the same as a DM planning a "brutal survivalist" campaign, and then having their entire campaign wrecked by a druid or ranger PC and a single first-level spell.
If the gunner finds himself facing a pack of wolves, he can take to the air and hover outside of their reach as he rains death on them.
Wolves are the
definitive example of how a DM might run an encounter poorly. Why are the wolves not stalking the gunner and awaiting an opportunity to attack safety, or better yet, not fucking off to find easier prey when the gunner proves themselves a risky target?
The threat of the acid that the villain is filling the room with is greatly reduced by your ability to hover safely near the top of the room while you look for a solution.
Which is why you do as Matt Mercer did, and make the focus of the acid pit trap not the acid itself but the time pressure put on the players to find and execute a solution,
which involved the characters' ability to fly and navigate the acid pit trap room despite filling with acid.
Again, that's not redesigning an encounter to accommodate flight. That's designing an encounter from the outset to account for
one of the most common abilities in the game.
This is not the case with things like the Broom of Flying or the Boots of Flying, which are designed with a more "set it and forget it" mindset, much like Overland Flight was. You don't have to worry about choosing your battles with them because their duration is so long that they functionally last as long as you need them to. For most practical purposes, they act as the ability to Fly "at will". That's why I've been saying that it's utterly bizarre that you cite these items as more balanced alternatives available for low level play.
They
are balanced alternatives available for low level play. There's no better example of this than the
multiple playable races which now exist in the game that get innate flight.
It is a core part of the game, not a potentially game-breaking bonus or alternative feature to be "unlocked" or used only in emergencies. This is not, conceptually or mechanically, like a vorpal weapon acting as a game balance bell that can't be unrung without brazen DM fiat.
As far as "dungeon crawls" go, a ten-minute duration Fly spell really is all you need. Most powerful spells or class abilities have a
one-minute duration for a reason: the average combat only lasts three rounds (18 seconds), and
players are expected to complete 2-3 encounters in rapid succession, then search the environs they just cleared and short rest. Most classes, spellcasters included, get core class abilities (and limited spell slots) back on short rest, specifically to accommodate this style of play. Fly, like most exploration-pillar spells (see, levitate, detect magic, locate object, clairvoyance), has that ten-minute duration to account for movement, search, and investigation times.
Anyway, again, I get that, it's just not what you see with any of the actual writing for the setting. Every city is swimming in magic items, magic guards, magic portals, magic shops, magic people. Even going out into the countryside people will get exposed to magic things constantly. Caravans, monsters, artifacts, armies. This is another clash of gameplay and verisimilitude. It's a world of adventure, so there are no peasants living normal peasant lives really, they're constantly being assaulted by something for the PCs to do, statistically to the point where villages shouldn't exist, but then it'd make things weird.
My personal favorite part of FR is how trade routes often go without maintenance or patrol, specifically because large trade companies and caravans so extensively use teleportation circle networks and magical travel, smaller realms can't sustain the infrastructure via taxes and tolling revenue.
All the same, don't forget that part I mentioned where whole-ass nations have expressly magical military forces, and/or spellcaster militias. Or as I joked once to a friend, Silverymoon is to the evocation school what Vermont is to guns.
Okay, but that really depends on what kind of setting it is, isn't it?
If I wanted to write a story about a dwarf with a cybernetic arm (which is a weird starting point, but okay), I'd have to narrow down settings which have dwarfs in them, then narrow it further down to settings where cybernetic-armed dwarfs are feasible. I don't have time to check my homepage for an IP list, but I'm going to go out on a limb and guess that cybernetic-armed dwarfs aren't that common in fiction. For instance, it would be far easier to get away with a cybernetic dwarf in, say, Warhammer 40,000 (via squats/Leagues of Votann, who aren't really dwarfs, I know) as opposed to Lord of the Rings.
They're literally just describing an artillerist subclass artificer in D&D, my dude. Incorporating the subclass' eldritch cannon feature into a prosthetic arm is entirely fine and permissible within the rules; this is very much a matter of "flavor is free". Frankly, artificers can do a
hell of a lot more than just that with a prosthetic, especially post level 10 and 11 once they acquire the magic item adept and spell-storing item class features.
This is exactly why artificer (along with druid) are favorite classes for players who want to play characters with disabilities.