A seven-game series every round means more action and excitement.
Yes, more games equates to more money for the league. We don't doubt this had much to do with the decision to expand the first round from five to seven games. However, that doesn't mean that we, the fans, don't benefit from this as well. Come on, who doesn't want to watch more NBA playoff action? Yeah, exactly.
If a team is really that much better than their opponent then they should take them out relatively quickly regardless of the format. Although it isn't common, there have been eight teams in NBA history that have overcome 3-1 deficits. Seven-game series FTW.