You're right PSG doesn't have any major contender in the French domestic league and offcource due to this, the French competition have become less competitive and quite boring to watch. When there's are less competition in a league,it becomes boring to watch.
Yes, however, it is quite boring when watching the competition in French Ligue 1, because it is certain that the winner will be PSG, however, what is interesting is the ranking after that, they are quite competing to successfully secure a ticket to UCL.