Halsy, what are you smoking? M.U.L.E. didn't set the bar for space sim games. M.U.L.E. was a multiplayer strategy/economy game.
Elite set the bar for space sim games. To quote Frontier Development's website, David Braben's (the creator of Elite) new company:
""Elite" set many firsts, and was the first genuine 3D game on home computers. Even many years after its release it is fondly remembered. For example "Probably the best computer game ever" (The Times, December 1988). It went on to sell around 1,000,000 units, and is popular still, having appeared on most popular formats. "http://www.frontier.co.uk/games/elite/