There are over 90 teams that can compete in international rugby with several forms of competitions.
ranging from the commonly known six nations and tri nations to things like the viking tri competition (can't remember exact name) which is comprised of Norway, Denmark and Sweden. Others which have pakistan, China and Indonesia.
I'll acknowledge that the skill level still has quite a gap between top teams and lower ranked teams, but the gap has closed fairly dramatically over last couple of years makes for some great entertainment even from club level. So trying to say its boring cause of handful of nations is completely flawed!
Cricket is a bit different, it has developed along with old colonial countries (so not all of them). I would not say this makes it boring, hence why the Indian Premier league has become quite lucrative (cheerleaders and the sorts) wouldn't get that kinda money or attention if it was deemed boring, just the argument between twenty20 and test.