I'm not a fan of the TNG interpretation of the Prime Directive, never have been. And, anyone from the Federation shouldn't be setting foot on foreign soil, which includes the star system, of a race that hasn't given them permission, regardless of the social/technological status of that race. The Federation is basically exploiting lesser cultures for information but offering nothing in return.
Who gave them this power and why should any human bow to it?
Are they protecting Earth, or are the protecting their slice of the galaxy from barbaric and unpredictable humans?
They are a far future cooperative of all species, consciousness’ and civilisations, from ‘far beyond the stars’, harmoniously looking after themselves and each other as a universal collective consciousness in a retrospective way through all of time and space via the watchers. Even though this state of future harmony has been achieved, there are still anomalies and glitches in the system as it is booting up to this ultimate expression of universal harmony and universal peace…. So using very advanced technologies, watchers are interspersed throughout the four quadrants to pivotal points in time and space to make sure that these focal points remain fixed points in time, as any deviation or corruption could lead to the collapse of this harmonious future where all species have reached the ultimate expression of consciousness and peaceful coexistence.