This can be confusing. And outside of that there were great people like Reb Chaim Solveitchik that simply did not let Musar into their yeshivas. To Reb Chaim, Yeshiva was for Gemara, Rashi, Tosphot. Full Stop. [This opinion, as far as I know, was shared by the Chazon Ish].
None of them liked the השכלה (Haskalah) which was the Jewish version of the Enlightenment.
The arguments against the Enlightenment itself seem to me to be appropriate the the Jewish version.
That is, starting from Jonathan Swift up to and including Johann Georg Hamann and Joseph de Maistre. I think you could include Allen Bloom, because in the long run his book is a critique on the Enlightenment from the aspects of seeings its bad effects (Closing of the American Mind.)
The most powerful critique is of course The Closing of the American Mind . Every sentence in that book contains a whole university education all in itself.
It is for this reason that I see the Rambam as giving a solution to this problem with his balanced approach (1) The Oral and Written Law of Moses (2) Physics (3) Metaphysics. That is he saw each of these as an important component of every persons's education. That is as universal and necessary. Sine qua non. Without which nothing else can happen.
My own approach to Musar is that it is like water. You need it but you do not want to drink so much as to overload your kidneys.
To me is is an essential vitamin, but I can not see how doing it hours every day [as the Musar movement intended] would help anything. There also seems to be no evidence that more that 30 minutes per day helps anything.
While Reb Israel Salanter was certainly right about the need for character development, learning tons of Musar does not seem to help. If anything, it hurts.
Instead, I suggest a Jewish version of the Boy Scouts, or like they have in Israel the "Tzofim" [Scouts].
That is to put it all together-- my idea of a proper education is the Law of Moses [Oral and Written Law] Physics, Metaphysics, Survival Skills, Music.
There are problems with religion that the counter Enlightenment does not deal with very well. But the experience of living in the religious world has convinced me the truth of Reb Nachman who said most teachers of Torah were demonic. תלמידי חכמים שדיין יהודאיים. Rav Israel Oddessar the founder of the Na Nach group certainly stressed this point and from what I have seen he was right on the money. So to my view this balanced approach of the Rambam make the most sense.
The problem is this. There are good arguments for the importance of keeping the Law of Moses, the oral and written Law. But as soon as one wants to do that, right away the Satan sends his messengers to mess the whole thing up. Most often the very desire to keep the holy Torah causes people more sin than if they had just remained secular. The way the messengers of Satan get into the door is by a kind of scam in which they try present themselves as Torah teachers. My impression is that the best thing to do with them is to shoot them on sight. [If not for the problem that that would mess up the drive way or side walk.] The enlightenment did not arrive in a vacuum. Nor did the Rambam decide to combine faith with Aristotle and Plato because of some whim. He saw faith a reason as being so connect that one could not exist without the other. Faith as we see in the religious world without Plato and Aristotle becomes fanatic insanity --not just for individuals but for whole communities. This is clear to anyone who has lived in a religious community. On the other hand Reason without the Revelation from Sinai is like a iron oven of ice.