Consider what is said by Picard, regarding the Bajorans, way back in "Ensign Ro". He says that: "They were architects and artists, builders and philosophers when humans were not yet standing erect."
Given that the Bajoran people didn't advance significantly in over 100,000 years, they were clearly stuck in a dead end, probably due to the d'jarra system and similar other factors. The Cardassian occupation brought that to an end, and possibly will allow the Bajoran civilization to grow and evolve, especially as a member of the Federation and a part of the greater galactic community.