Robert, first let me dispell the myth that some people have regarding the Ninja in terms of weaponry; the Ninja were (and still are) 100% focused on effectiveness and practicality, hence if you gave/give someone who practices real Ninjutsu the option between going into a life or death situation with a Kusairgama and an M4, they are going to choose the M4. For most of their history though the Ninja were of the peasant class and thus did not have access to the superior weaponry of their day; their primary use was also espionage even at later periods in their history. Thus they had to rely more on deception, surprise, disguise, camouflage, and stealth to overcome superior odds, superiorly trained adversaries, or superior weaponry.
To this end they often hid weapons in common or inconspicuous tools or in other weapons. Kama were a common tool used for reaping rice and therefore would have been a readily available tool for the peasant class to access and possessing/carrying one would likely not have raised suspicion. By hiding a chain (Kusari) in the handle the Ninja could significantly increase their range or ensnare the swords/weapons of a Samurai if forced to do combat (which they generally tried to avoid or if they were forced to do so were usually looking to escape or cause damage and escape rather than going “toe to toe”). So they weren’t necessarily designed for all out battlefield combat like the Katana, Japanese Long Bow, or Naginata, but instead more as weapons of surprise, multi-purpose, and accessibility.
A good comparison would be comparing today’s CIA/espionage agents to today’s Marines. Both have effective weaponry, but neither one’s weapons would be great in the other’s arena of application.
So, no I would not rather have a Kusarigama than say a 9mm if I had to defend my life or the life of a loved one, but I can still appreciate the concepts behind a kusarigama and how those can translate to other combination weapons, and could use one effectively if I had access to one.