why in the original Naruto does Naruto not use the power of the 9 tailed fox oftenly ?

All of the tailed beasts are hard to control.  It takes time and training to befriend them.  But 9-tails is the hardest of all as he is more arrogant and as you watch the series you'll see that he gets betrayed a bit by humanity, leaving him very bitter.

Kurama (his true name) wants to take over Naruto so he can escape his prison and enact revenge on the world.  When Naruto lets Kurama out, even partially to create charkra tails which powers Naruto up, Naruto has no control and often no memory.  He blacks out.  And in one storyline, he hurts Sakura in that state.

Even tapping into the Chakra to do regular jutsu is dangerous and requires training to do safely.

Because he doesn't know how. He only learned how to tap into the power during the Chuunin Exam. Then he achieved the cloak when Sasuke was leaving. Then the rest after that was fillers. Then Shipuudin happens.