To the Ari the Will is everything. It breaks through all barriers. It is clearly a causative agent. And I agree with this. I think modern psychology has way too much accepted the doctrines and Nietzsche and not realized that the will has the ability to overcome all personal flaws and mental problems. [Though they dress their guesses in scientific language to impress people. Feynman openly called all social sciences pseudo sciences.]
My own opinion here is that I don't know if there really is an argument.I would first have to see which will Nietzsche is attacking. It seems to me unlikely that he is knocking the actual will of Schopenhauer (the higher Will). Sure he knocks Schopenhauer but in terms of what Schopenhauer though people know they are willing something. Not in terms of the will as the dinge als sich alein. Maybe I am wrong but it seems more likely that he is attacking the individual will, i.e. what people call their will. The more basic thing I think is going on is Nietzsche is trying to attack free will which Ari clearly holds from.
If you believe in free will, obviously the will is going to play a large role and not just the higher will but the individual will.
 The other issue I wanted to deal with is Constant the French aristocrat that saw the genius of Rousseau but also his flaws. The difference between the freedom of ancient Athens and the freedom of the moderns.
But the pure secular is a empty of content. [I mean meaning of life type of content] so clearly people have a good motivation in getting involved with Torah in a Lithuanian Yeshiva.
I am reminded of a televised debate [or discussion] in the 1980's between the USSR and the USA.
Someone asked a woman on the panel about their attitude towards sex in the USSR. She said, and I quote, "We don't have any sex in the USSR."
() My own perspective on this is towards the Schopenhauer and Ari axis.
() These two subjects are related because if you think like Nietzsche that the will is nothing then free will will also mean little to you. and if free will means little then why bother letting people do what they want.? This is the reason freedom has suffered in the modern age. If people are determined then why let them be free. This is the reason why totalitarianism of the Democrats today in America has so little appeal to me since I see freedom as a prime value.