When I started learning to roast coffee, I roasted only for brewed coffee, not extracted coffee (espresso) mainly because the process of making an espresso is complicated and I would have to learn it as well. If the espresso tasted bad, I wouldn't know if my mistake was in the espresso preparation or the coffee roasting process.
Another reason I focused on roasting only for brewed coffee was because in brewed coffee you have the potential to better experience the full flavor profile of the coffee. George Howell often relates brewed coffee to wine and espresso to brandy and this is why:
Brandy is distilled wine. The distillation process separates the useful parts of the wine from the liquid parts through evaporation and condensation, creating a more concentrated end-product.
Espresso is similar to brandy in that less water is pushed through ground coffee at high pressure, resulting in a higher concentration of total dissolved solids* in the final product; the espresso.
While I greatly enjoy espresso and have an espresso maker at home, when I roast coffee, I focus on roasts for brewed coffee because I find it to be a truer representation of the coffee's flavor profile, created at origin.
- The amount of the useful parts in the final product is measured in Total Dissolved Solids or TDS.