CapnZapp, I would suggest that, whatever WotC design intent is/was, it was not to "dumb down" stat blocks. That has a strongly negative connotation that I don't think you intend. It implies, at least to me, that those who use the standard stat block are dumb as well. I would suggest that they (WotC) have offered simplified or modest stat blocks that take a degree of system and rpg mastery to get the most out of.
Personally, I don't think any edition of D&D, or any rpg I have ever played or owned, has had monsters that cover all of my needs. So I guess I have always assumed I would need to tailor them to my needs. For that I find 5e very accommodating, more so than any edition of D&D I've played (1e, 4e, & 5e). Now, if that is a result of them making the stat blocks simpler, than for me it was the correct move.
I find this even more true with high level play. It is, for me, fairly easy to adjust 5e monsters to accommodate different threats.
To each his own. I know WotC are able to offer up more interesting stat blocks at high-level because the two last editions offered them.
Yet, they chose not to do so this time. It's hard to not get bitter about it since it seems they get away with (much) less work for more money. It's hard to shake the feeling they offer just enough high level support this time to be able to say they have that support, but when customers actually try it out it falls apart rather quickly.
These two arguments are so worn out and illogical. I'm getting tired of having to counter them each time.
I hear the "the Dm can do it himself" all the time. I'm getting sick and tired of that defense. It is utterly irrelevant. I
want to pay WotC to do it for me.
I also hear "No matter what WotC does, you need to tweak things your way". This is relativizing of the worst kind. This does not mean WotC should get away with not doing a good-enough job in the first place.
My expectations are that each new edition should improve upon the old ones. 5E is a disappointing step backwards in some regards.
Yes, 5E is "accomodating" in that it marries the great idea of 4E that monsters doesn't have follow PC rules. Creating NPCs in 3E was a nightmare. But none of this explains or excuses the way high-level monsters aren't even given rudimentary tricks (tricks I definitely don't have to explain to you Dave2008, since you are a master of them yourself).
Look, it all boils down to one single thing.
In their anxious attempts to make 5E a success (which was far from given before publication), they have decided to treat high-level play as just more of the same as low-level play. Perhaps they were afraid customers would look at a CR 20 stat block and be scared away.
But the reality is that at low-level it's okay to use that strategy. But almost none of their applied choices (non-complex stat blocks, bounded accuracy, etc) really work above single-digit levels.
The game desperately needs a whole new layer of complexity and nuance for those of us who DM experienced players. That's far more work than can be expected from any single DM.
You are apparently content with changing practically everything at high level. I'm not. I expected 5E to shine from the extensive experience of four prior editions, but I simply don't see it.
High level 5E play feels.... flat. The design feels naive. Simple somehow.
Like as if the newb players that start the game remains as clueless and non-performing even after levelling up their characters to level 15 or 20.
In my experience, there is no such thing as a newb high level player. By that time, almost every player will rip the default 5E challenge to shreds. Simple, accessible and direct - those are valuable design goals at low level. At high level not so much.
Of course I can fix all this. But I need to do much more work than I want to. I'd far prefer a more complex and more challenging tier III and especially tier IV baseline. I might still make tweaks here and there, but it would be far less work to get to where I need it to be to properly challenge my players.