0-15-30-40 within the game - why? I mean why there is only 10 gap between 30 and 40 and not 15? Someone who wrote the rules had problems with math?
I'm sure there's some history behind the scoring system, probably an interesting story, but I agree it does seem pointless (pardon the pun!)
In the beginning, both rackets and tennis scoring were used for lawn tennis. With rackets scoring, a game comprised 15 aces, which could be won only by the server who remained "hand in" until the loss of a rally. Tennis scoring was adopted for the first Wimbledon Championships in 1877 and became the standard.