They need enough volume for it to be worth doing. I think consumer chiplet-based CPUs are sort of piggybacking off the server chiplet-based CPUs, but if you made special desktop-only chiplets, then you'd have to sell a lot of them, to make it worthwhile.Could AMD not make lower core count chiplets on a cheaper process to fill in those budget CPUs, or even two different chiplet sizes on the currently planned node for the cheaper CPUs with lower core counts? To my understanding, the cost is determined by the die area so the smaller core count chiplet would not cost more because they would be a smaller area. Packaging would become more complex though.
That's why I think they have mostly a 2-pronged strategy of designing chiplets for server and desktops (and high-end laptops), plus designing monolithic APUs for laptops and desktop. If/when their mainstream laptop APUs adopt their chiplet architecture, then you might find a bit more creativity in the desktop market.
IMO, it would be really interesting to see them bring their C-core chiplets to the desktop. They wouldn't be cheap and I probably wouldn't buy one, but I'd be curious to see what sort of multithreaded performance they can achieve with a 32-core/64-thread CPU in an AM5 socket.