A seven-game series is a battle. Playing a single team up to seven times in a matter of two weeks lets each team know the intricate details about the other. Things that may have previously gone unnoticed by one side will no longer be missed.
The most important thing about a seven-game series is that it allows for mistakes to be made. A game can be played poorly by one side, with the goal of winning four games out of the seven still being alive. The team that makes the fewest mistakes during the series is the one that will prevail. In a series that features so many games, the better teams are often the victors.
Teams like the Indianapolis Pacers, Miami Heat, San Antonio Spurs, and Oklahoma City Thunder can afford to drop a game or two along the way because they are all capable of winning several in a row to ultimately win a series. The Charlotte Bobcats and Portland Trail Blazers of the league must play their best basketball every night with little to no mistakes being made.
The playoff format is designed to benefit the stronger teams in the league. This is not to suggest any type of passive conspiracy, but rather acknowledging that a seven-game playoff series is much easier to regain control of than a single game, such as in the NFL.
Just ask the Pacers, who were down 3-2 to the Hawks before waking up and winning two straight to advance to the next round.
Even though the Pacers had their struggles at the end of the season, and in the first five games against the Hawks, the length of the series against Atlanta allowed the Pacers to start playing like the top seed in the East once again.
Same goes for the Thunder and Spurs, as both went to seven games in the first round, but pulled out double-digit wins in their respective Game 7s.
This theory does not really apply to the Heat as they are seemingly unstoppable until at least the Conference Finals each year. They have gone to a Game 7 in the past two Conference Finals against the Boston Celtics and Pacers respectively, but won both games by double digits.
The system in place in the NBA is one designed to benefit the league financially and also the fans. It allows teams that are surely not going to win the title a chance to compete in the postseason, and a win or two for fans of the lower seeded teams is a great experience, one that is unable to be explained to fans of teams that frequently miss the playoffs.