Yeah think it's a symptom of Rules As Written evolving under "rulings not rules" into Rules As a Guarantee & it's probably somewhat related to your be honest fair comment being built on a patch of rules that are quicksand or lava for the gm.
Yes excellent point about rulings not rules.
Back in the old days it wasn't as difficult for the GM to make changes for flavor/tone/style/etc or look at a situation in play and say "because of [thing that happened/was done/is present] I'm going to change this one rule for this one time [like so]". sometimes that one off change partially or fully favored the players over the original rule and the important part was to strike a balance between tough but fair vrs rule of cool. With much of 5e the rules took that option away from the GM by writing a particular rule or subsystem so it would be almost impossible to hinder a pc under normal play without the gm just completely throwing out a rule written to be a guarantee with no safety net serving the gm. Players who might have been a little bit on edge but grudgingly accepting the gm saying "yea you did x y & z, that would make [thing] a little easier... But I don't think it's enough to ignore the rule standing in your way" just look at a rule like resting and recovery encumbrance the missing container/body slot rules or whatever and see it as the absolute guarantee that wotc wrote because the gm who changes it to be stricter is simply cheating rather than making a ruling on an unclear rule given the absolute clarity.
Incorporeal creatures in my campaign have the touch attack (per 3x) so they ignore armours + shields except for the enchantment mods (if any). Obviously Shield, Mage Armour and the like work.
Knowing something about the Tethyrian War is a general INT(history) check. Trying to know something specific about that war is with Disadvantage.
Sanity is a 7th ability. Now characters have to determine if they wish to spend ASI on Sanity as it its use becomes more common at the higher levels as PCs explore the weird and terrifying.
I'm not completely heartless but high level has its dangers. It doesn't always come down to damage and hit points.
We use racial age in similar fashion from 3x.
The barbarian tried to defeat an intelligent weapon and found himself trapped within its "world".
I asked the barbarian to take his Traits Bonds Ideals and Flaws (we have many more than the usual) and allocate his hit points as he wished to each one according to importance. The intelligent weapon represented as a hag battled him with each strike doing psychic damage (could not use his barbarian ability to halve the damage). The damage done was randomly allocated to his TIBFs. Once a TIBF reached 0 it was erased from his character sheet. They did not return once he defeated the hag (spirit of the weapon). A Restoration would be needed to restore each one lost, but they were now stricken from his memory.
Earnestly I could give many many more examples to how I have tailored the game...
I just find I'm able to bring about thematic elements much easier with the system of 5e than those of the 1e-2e. And my players trust me not be a xxxx about it.
And to give a fuller picture our houserules also provide many many perks.
I really do not agree that 5e is limiting in any way to be honest. It's actually quite liberating and that's predominantly because of the engine. What you really need is a table of like minded people that trust you to be fair and are open to suggestions.
The table decides at the end of the day.