If team 7 trained together then Naruto would never have met Jaraiya. Then Oro's seal would have never been un-sealed. Naruto would not have been able to control his chakra or Kyuubi's. Naruto doesn't need to be trained by the likes of Kakashi anyway. It's as Jaraiya said, Naruto's kyuubi chakra is just wasted by doing these low level jutsus. Naruto just needs to hurry up and learn the high level death jutsus (just like the fourth). There's no need to play with little ants.

Besides, the introduction of the super pervert was extremely important.