Communications missions require power. Power is directly relate to solar surface area and the mass required to dissipate heat. That all leads to a larger satell

Communications missions require power. Power is directly relate to solar surface area and the mass required to dissipate heat. That all leads to a larger satellite. Once you get to a certain size/mass, it's best to just park it in a GEO slot, since the dwell time is 24/7 (as opposed to 6 to 9 minutes of contact time in LEO).