Dont you think that the King's Indian Defence is too defensive... And played mostly by the players with a drawish mindset, of course for black. I personally, experienced a number of cases.. where d4 was countered by Nf6 or g6. with the flianchito and an early castling. Well dont you think that black is slightly on backfoot playing this opening.

Not at all!

The King's Indian Defense falls in the "hypermodern" school of chess thought.  Black allows white to set up a center with the view to strike back, or fix the center, having taken his time to set up a foothold on one of the wings. As for a KID player with a drawish mindset? The difficulties that black has undertaken make this one of the most cutthroat of openings.

I could continue to rant, but there is plenty of material on the opening. I would avoid the article here on chess.com, but there are plenty of others. The one on Wikipedia seems pretty good, although a little skeletal. If you have any specific questions, you could always send me a message.