There's no point adding the tenth ham sandwich to the market. Make your monkey brains game and if only three people like it so be it. Maybe three thousand people will like it.
I agree, but also don't, with this statement.
I think it is important to understand what the designer is designing for. Let me use two different examples.
1. I will often design new bespoke games (rules lite games) for my table. I think it's fun to do as a one-shot. When I am doing that, I am designing the game knowing that I do not need to sell the game. That the players all play in good faith. And that the purpose of the one-shot is to have a good time. I don't need to worry about issues like commercial appeal, or that there might be a balance issue, or that the players might try to find some loophole. Moreover, I can design the rules lite game knowing that the table is already familiar with the conventions of FKR/rules lite games!
In other words, I can get my freak on when I am making those games, because it's for a small and selected audience that I know.
2. On the other hand, Crawford and the designers at WoTC have a different remit. They aren't designing for themselves. They are designing for Hasbro. And their remit, either explicitly or implicitly, will be to design a game that:
a. Maintains D&D dominance in the TTRPG market.
b. Sells all the copies. ALL UR PROFITZ R BELONG TO HASBRO.
c. Makes current 5e players happy, while appealing to new market entrants.
d. I'm not positive on this, but I assume they have been working with the VTT/DDB people to make sure that changes are easily expressed in whatever boondoggle they are creating.
I assume that if they were designing the best game for themselves, it might be different. But they aren't. They are designing within the limitations imposed by the fact that they are employed to maintain the brand.