The main difference between deathrace and something like Boss Battles or Jailbreak is atleast it isn't getting stale because of the routine stuff you're doing.
BB: No goal to work towards. Shoot at the boss and hope you don't die long enough to kill the boss. Maybe buy a title after 100 rounds.
Jailbreak: The issue with this in games such as Garrys Mod and TF2 apply here, but here there is no Mic. Wait for commands, one dude slips off, riot, get guns. More boring than boss battles
Deathrace: Buy different weapons, work as a team, destroy other cars, constantly different maps. Work towards buying your favorite weapons and devise strategies to be as efficient as possible, engaging to as many players as can be at once