In the end the sport is less intense then it looks, no way out = tap and end of the game. Sportsmanship and trust are essential in your training partners. The tap and the lack of punches and kicks makes BJJ one of the few martial arts where 100% intensity can be spared without physical consequences (something that is virtually impossible in kickboxing).
In our opinion, the tap and 100% sparring provide some very important mental aspects that are developed when practicing BJJ. For example, the EGO is kept nicely in hand. You can't pretend to be better than you are. Every rolling session (sparring) at the end of a training lets you know in detail where your skills and mental attitude are. You are confronted with yourself every training session and literally forced to look at your own place objectively. Talk doesn't work on the mat, but performance does.