The slow speed is hiding the fact that they are out of ideas that can fit in the current race, monster, and class systems.
Then why did they launch the edition at a slow speed?
By that logic they started with no ideas
There is no path forward with their strategy. They have at most 2 years before major slippage. And 2 years is kind. Path of the Wild Soul? They are nearing the wall. It's Go wild, Revise, or Restart time.
2020 was the game's best year
Why would they revise and restart and risk losing that?
3.5 Ed had poorer sales than 3.0 Ed and 4th Ed lost the market lead. If they revise now they risk losing everything they've built
The bottom of the barrel is where patience & tolerance for stagnation ends. There is only so much patience that can be expected of people who notice crack in the 5e rules foundation over time or just find themselves bored with the level of mastery they've acquired over a very very simple ruleset that minimized tactical & resource management elements.
If they revise now, do you really think they'll make the game MORE complex?
They will likely go the opposite direction and make DnD even more streamlined and simple
What's more is that they are entering the d20 era of not d&d 5e versions of 5e spinning off away from wotc's stagnant d&d 5e. I can think of 3coming out in the next year
(stargatehoenix, levelup, anime5e) with two in the next month or so & all of them taking it in remarkably different directions with their own rules modifications that will continue to diverge from the core it started with just as paizo & pathfinder did.
PathFinder only had a chance to pass DnD because they launched a new edition people didn't like
Level Up is unlikely to be the new PathFinder unless DnD lets it
TCoE probably did more harm than good wrt continuing a slow pace aiming for geologic timescales. People who were already scraping bottom or at a point where they could see bottom on the horizon heard it get talked up like the next unearthed arcana/phb2 with empty talk about new rules new variant mechanics etc. When it finally came out there was a reprint of some gm facing stuff, a handful of player facing options, and... and.... it's still basically the exact same game leaving everyone with expectations feeling like charlie brown watching lucy yank the football away even more dramatically than the last few times.
Sad for you and I and anyone who has been gaming since launch. But we don't matter anymore
There's more people who just started playing and haven't been playing DnD since 5th Ed was released. Who aren't burnt out from the limited options
That's the audience now. D&D can lose every single player who started with 3rd Edition and earlier and still chart high sales on Amazon and be a huge hit