Depends on what you mean by "doing this." Having them in a lower orbit means smaller equipment required to connect, lower latency compared to connecting to satellites in GEO, and smaller lower power satellites. To get those benefits they have to be close which means more satellites for full coverage.

Also it's not like even this particular orbit will be full when SpaceX is done at 1150 km orbit the 4425 satellites would each have a bit over 80,000 km^2 to themselves on average if they're spread out evenly.