Because he was able to achieve independence for India without war.
Some Indians feel that after the 1930s, Gandhi although by now world-famous, was in fact in sharp decline. Did he at least "get the British out of India?" Some say no. India in the last days of the British Raj, was already largely governed by Indians. ... and it is a common view that without this irrational, wildly erratic holy man the transition to full independence might have gone both more smoothly and more swiftly." The Gandhi Nobody Knows, p. 12.
I recommend reading the entire document as linked above in post 16.