Who's gonna switch to 5.5, and why?

[KorvinStarmast]

The KISS rule was your goalpost, not mine

It's my criterion based on their 2014 design goals for the basic game engine, and I don't like how they have departed from it. (And they departed from it about the time Tasha's came out, so this isn't new to D&Done).

As to the monk attacks, current 5e is KISS: once you are level six, all attacks are magical and that more or less ends "is it resistant/immune?" during combat damage resolution. Much simpler than what they are doing with "Oh, yeah, force damage as a rider" currently.

The KISS solution is to do away with resistance to nonmagical attacks entirely, except when it is highly thematic.

Not gonna disagree. But they did the resistance thing to get away from the DR fiddly bit in 3.x, right?

But does every high CR monster need this?

Short answer is: no.

Does it add anything to the narrative? It could, with a proper DM and a game where these creatures are major threats, not encounter #2...but this rarely manifests ime. In practice, the DM has to halve a bunch of numbers for no good reason.

A fair critique.
I have gotten used to it, but I also need to do more prep each time I pull out a new monster for the party do interact with.