Rivals Attack Modi Over Economy

Political rivals continue to snipe at Modi over India's lack-luster economic growth data:

http://economictimes.indiatimes.com/news/economy/policy/pm-narendra-modi-facing-backlash-as-discontent-over-indias-slowdown-deepens/articleshow/61045652.cms

What I feel Modi's govt should have done is to devolve powers over key economic policies - like labor policies, minimum wage, land reform, etc - to the state and local district govts. Doing this would have allowed those state and local govts who are more boldly inclined to proceed more aggressively in reforms and thus boost national economic growth, while the state and local govts with less inclination would have been able to lag according to their preferences. This would have entailed no political backlash cost for Modi directly, as the ensuing reform decisions by various state and local govts would be on their own heads and not Modi's. It would have been a way to jump-start reforms and spur competition between various parts of India in reforming themselves faster in order to reap opportunities faster. I don't understand the purpose of keep all authority over economic policies so tightly in the hands of the Centre. When there's no political cost to doing so, and when there's plenty of benefit to be gained, then I don't see why Modi's govt hasn't proceeded in this direction.