It is very possible to present mysterious new cultures, as long as you don't dress them up with words the brain cannot read or pronounce. A sin Pillars of Eternity is especially guilty of. When you can't read the arcane name of something, it gets stored in memory as "weird name" and when there's more than one of those they all get jumbled together and the brain stops caring.
There is plenty of time allocated to writing RPGs these days. The primary issue is that too much of it is spent on volume of words, and not enough is spent on quality and brevity.
I think there needs to be more linguistic focus in RPGs, with conlangs etc. True realism can only be achieved by this way; many RPGs are gratingly unrealistic linguistically, which detracts from the world's believability. Ideally, there should be diachronic conlanging, but that is too daunting for many.
A true realism could be created only if the creator/writer have real live experience,and asking questions about how some thing will work,and asking them about every thing.Sadly this decade most people's real live experience ends with tweeter and tumblr.
The problem with needing actual real life experience to make something accurate is experiences are very limited. I doubt anyone alive has been in a large battle with hand weapons. And if anyone has been involved on either side of a cavalry charge they are most likely living in a society with limited computer access and little knowledge of rpgs.
Also, people experience things differently. I have been in combat, but my experience is nothing like that of storming a beach in WW2. Or being at constant, brutal war for years like in WW1 and 2 for various European countries. My experiences are nothing like Alls Quiet on the Western Front. Modern day combat is usually short lived and for most of the time you are in relative safety without the oppressiveness people living in trenches for years, under constant threat of death almost all the time.
People also react differently in combat. I got tunnel vision which kind of blanket out everyone but me and my target and time was weird. It slowed down but not in a good way. This hurt me as I was supposed to be directing my team or squad, not in my own world oblivious to what was going on around me and outside my tunnel. But that doesn't happen to everyone, but is kind of common. My friend was freaked out the whole time and completely aware of everything and more observant than usually, but too freaked out for it to be a good thing. A lot of people are fine until rounds start flying, I was anxious and couldn't wait for and was relieved when they did. Not because I wanted to shoot at people or be shot at, but because it is better than waiting. I hate waiting.
Remember that Gurkha that killed like 30 attackers on his own within the last decade? His account makes it seem like he was present and aware and completely functional the whole time. I wish I could say I was like that. I'm not a coward but if someone was coming up behind me or on my flank in a fire fight I honestly would never notice it if I was alone and shooting at someone in front of me.
Also keep in mind that even the major battles of this century have been nothing like WW1 and WW2 where more people have died in a minute of some battles than in all the battles of this century. And their battles where nothing like when people used muskets and lined up. Which was nothing like when people used hand weapons. Anyone who has been in a lot of fist fights can probably agree that when you get completely winded you kind of stop caring so much about being punched. Was it the same when instead of a punch you'd get a spear or a sword?
Also, the more accurate rpgs are usually very annoying. I forget the name of the game but there was this one game that aimed to be pretty realistic. Your shield and weapon would break a lot. I ended up usually throwing spears and trying to keep my distance. Trying to fight up close against two people was usually a lose unless you got lucky. You versus three was impossible for the most part. Most of the combat rules and rpg rules led to cheesing battles, and it didn't encompass moral. I think most sane people would run from three armed people trying to kill them. I don't think most people want to play a game where they lose control of their character and run like a baby all the time.
If you think about it any realistic rpg system would be based around not dying instead of winning. I just don't think actual realism is what people want. People complain a lot about all the rariety of hitting in the old DSA system used for the RoA trilogy, and the critical fumbles, and weapons breaking, etc. I'd much rather have a very good and complex and interesting rpg system over a realistic one.
I think for settings sensible is a better aim than realistic. But, how much would people complain if there was no options for the modern day morals? People hated that there wasn't more options to save the orphan kids in the main Viking city. People want to be the hero as they believe heroes would act. If you had a setting where acting as most people day believe a hero would act gets them killed all the time, forcing them to make decisions they morally disagree with and anachronistically inserting into that setting, I think it would get far more complaints than praise.
Its also more noticeable in games that strive for it. When I wasn't allowed to do something I think my character would do in AoD it was way more annoying and noticeable than in Underrail. But AoD strived for options in dialogue where Underrail didn't so my expectations where different.
I, personally, like when a game allows you to do what you think is the right thing but attaches a cost to it. In TToN I kept that little girl in my party even though she sucked because my character wasn't a huge dick throwing little girls to the wild. It certainly hurt my combat performance. In Tuerigard and the Alliance with Rome it had things like setting the your slave free hurting you and the slave. There is also a mod for an overhaul mod of Skyrim that makes it so if you worship one of the good gods you have a limited number of times you can steal or assault people before they rejected you.
In my opinion you should be rewarded for doing what is the norm for the setting while being allowed to act otherwise, but acting anachronistically has a negative price. This also means no good points and bad points as that usually means equal reward and just picking a path and following the side that gives the most reward. Same with a karma system. It has the opposite impact of enhancing roleplaying, and curtails it or hamstrings it.