Well, yes, Inside Scoring is more efficient and reliable than Outside Scoring most of the time. But in a close game, the outside team has a huge advantage - they can score 3s reliably, which is the main way of cutting down the opponents lead.
Think of that in the terms of the NBA Finals: The Mavs are an outside shooting team (basically playing some slow Motion offense), while the Heat score inside more often (basically playing Look Inside or Outside Iso). So what happened in most of these games? The Heat worked towards a nice lead, but once crunch time arrived, the Mavs defense shut down the Heat offense, and the Mavs came back with their threes, winning more often than not.
So yes, shots close to the rim are the most efficient, but hitting 3s is the best way to win close games (besides making your FTs). LI will give you lots of blowouts, but if it gets close, outside tactics are better.