Things would look a lot different if there was only 1 single company that dominated the console market, for a start they would have a much higher price tag on their machines and games, as there would be no-one to compete with for sales/value and then expensive research into new technology wouldn't be in such high demand and things would just lie stagnant.
Competition is the main reason companies keep prices as they are and bring out new ideas to grab your attention, without competition there would be no progress (well, not progress at a very fast pace anyway), just ignorant control.