Regional Geomorphs

Why does every campaign you buy have to be an entire continent? Half the fun of being a DM is creating worlds so why steal that? There is the time issue but that's not really an answer. I don't think published modules should cover so much territory in such limited detail. 

I'm thinking of Regional Geomorphs as the title says. IMagine if TSR had develop a micro-setting (like the wilderness in B2 but a bit bigger) then dropped B1, B3 and B4 and others into that setting to really populate the Regional Geomorph with adventure and create a sandbox. Then develop a micro-setting for C1, C2, etc. That second setting could be next door or miles away. Encourage the DM to create a world but enable them to drop these microsettings into their creation.

This is a far more useful level of information for a DM to work with. The DM could then handle the big picture (or not, do adventurers really need to know the extent of the continent in most cases?

If the idea happened now DMs could homebrew their own and make it available (for sale or free, you do you). A DM then starts with one and chunks together a greater world when the players start to explore near the edges.

The only sticking point would be Gods and the Cults that worship them. Cult Geomorphs is another place it would have been nice if the DIY side of the hobby had explored. Imagine if DMs wrote up their religions and posted them online for free, or sold them, and other DMs would have the ability to pick and match however they saw fit. 

I'm imagining a buffet approach to world building and I think it would be better than what we have now with the Meh Forgotten Realms dominating a massive section hobby.