No it is not pointless...It enables athletes to test their ability against others from other countries.........Remember there are 71 countries competing in these games not only do they share a common goal of trying to win. not only for themselves but also for their country. Many friendships are formed by these athletes, ideas exchanged and so on.
Many of the smaller commonwealth nations have next to no chance in the Olympics because of the might of USA, China and the former eastern block, but put them into the commonwealth games, different story.
Bit like our LOC bowling meet last July, but on a slightly larger scale :D