"Original Monkees' songs were produced very thinly, on purpose"

This quote by Peter Tork is referring to the production of the initial Monkees' songs. He is suggesting that the songs were purposefully produced with a thin sound. This might imply that the production was carried out in a way that was not excessively complex or layered, and that the noise was kept reasonably basic. This could have been done to produce a specific environment or to stress particular components of the song. It might likewise have actually been done to produce a particular design or noise that was special to the Monkees. Whatever the reason, it is clear that the production of the initial Monkees' tunes was finished with a specific function in mind.