But hasn't satellite technology changed significantly in the interim since 90's with much smaller payloads i.e CubeSats and FemtoSats. These should theoretically result in lower deployment costs:
Sure, but smaller payloads == smaller capabilities. Telecommunications satellites need massive switching capabilities and also massive power. They also need large antennas to service particular areas and they need propellant to maintain their orbits. How many CubeSats would be required to stream HD video to many thousands of people, for example? Not saying it can't be done, just saying that it isn't an easy problem to solve and there has been a lot of money already spent trying to solve it prior to Musk's announcement.