You're comparing spell slots for players vs a DM having to keep track of 3-4 monsters with different abilities, some of which have spell slots as well. Novice DMs running a high-level one-shot like this Vecna one-shot are all but impossible in the old system.
Yes, I am comparing it, because it is about
LEARNING THE GAME, whether you are a player or the DM.
If you want to be DM, you should understand that you will have to work harder and learn more. A novice DM who one-shots a high-level adventure is very likely going to make mistakes (probably several), no matter how much you simplify creatures.
I see new players struggle with all aspects of the game, so let's just get rid of action economy as well. You get to do one thing. No bonus actions, no reactions, no Extra Attack.
Every step you take to make the game "easier to learn" is fine. As myself and others have stated it would have been better if WotC did more work on supporting
how creatures should be used/played instead of just on what they can do.
And many DMs on all social media have talked about how they feel they can finally comfortably use spellcasters as monsters now due to the new format.
So? People rarely post about a system that works well for them, they post about systems that don't and THEN will comment when what didn't work now does.
Lots of new players (and DMs) understand spell slots, enjoy the variety of spells and learning the options of everything they can do. Since that was the current system, you aren't going to hear them posting about how well it already works for them unless they are addressing someone who is struggling...
Your small sample size is reflective of the bias you have for spell slots on monsters, which itself is based out of your long history with the game. You need to recognize that there is a huge audience outside of your sample size who were very much unwilling to engage with the challenges of spell slots.
And you should recognize there is a huge audience of people out there who learned the game
with spell slots (again, even DMs) without any issue whatsoever for decades in many editions.
On top of that, you have to recognize the inherent irony in your words. You argue that you have the experience and skill to do this, but you don't have the experience and skill to add in a few more spells to your monsters? If you can master 25 spells on a lich's spell block and run it comfortably, you can easily add 5-10 more spells to the neo-lich spellblocks like Vecna.
There is no irony. I said WotC would be better off keeping spell slots
and adding the new features, and include a guide for novice DMs on suggested spells to use. If anything, WotC is hamstringing DMs by limiting the options when they present a nerfed spellcasting system for creatures. My suggestion is the best of both worlds. Novice DMs have advice and crib notes to help them run the monster, experienced DMs have the full list of options. There is no "more work" involved for novice DMs with my idea, so why do you insist on your way (keeping the new format) and making more work for me and other experienced DMs???
Anyway, to me this is like learning Chess. Each piece moves its own way. It takes time to learn and remember how the game goes. But once you learn it, playing is easy enough IME--mastery is what is hard, of course.
The truth? The game lacks one big thing. How to DM effectively.
Yep. That would be the biggest help for novice (and even experienced) DMs...