Chocobo Racing is "only" very popular when new high MGP cost rewards are released. Many players race hours and hours to get that 1st place of 1000+ MGP per 1.5 minute. With 4+ players the chances of losing is very high, and the reward of 200-300 MGP plus BONUS EXPERIENCE is ridiculous, and at this point there are better ways to grind.
More players should increase the MGP gain, not experience. At least in R-300. This will incentivize more players to race.