The Jedi weren't always a pure philiosophical group dedicated to the balance of the force. When they first started getting organized on the galactic level, they were simply a group of force users trying to expand their knowledge of the force.
In a few centuries, the jedi masters in the jedi council will implement restrictions based on what they have learned. Everything that leads to the dark side has simply not yet been figured out. All masters and padawans really know is to try