Apple's strategy too?
Third parties implement the feature and then you pay $9-$49 for the software. Sometimes you can add $4-$19 for a software update for every OS update.
It's a great ecosystem for developers.
And Roomba only moves in a plane as a result of its (slow) actuators, whereas an iPhone X tries to do hyper-accurate 6dof real time position, from a very quick external source (your hand), for augmented reality. Thus the sensor and computation cost premium. But that does not apply to the Roomba.
If they manage to solve that case, then the benefit of retaining the map is less compelling. By definition, you can do an adequate job without it. So then it's a question of what you gain in cleaning performance/efficiency vs. the extra complexity and any potential problems it might bring.
- It is obviously useful to plan cleaning.
- Once calculated, storing them should be cheap.
- Detecting that the stored map is wrong if you manually move the Roomba to another location should be an issue; just ignore the stored map after too many inconsistencies with current reality.