Are the laws of the sacrifices a concession to human nature, not to be repeated in the messianic age according to Maimonides?
Rabbi Arthur Hertzberg Certainly thinks so, writing:
In the twelfth century Maimonides, the greatest of all rabbinic scholars, explained that animal sacrifices had been instituted in ancient Judaism as a concession to the prevalent ancient practice of making such offerings to the pagan gods (Moreh Nebuhim 111:32).
In his essay Purpose of Sacrifices, Rabbi Dov Linzer states the following:
Rambam states that worshipping G-d through animal sacrifices is not ideal, but the people at the time of the Giving of the Torah could not conceive of any other form of worship. If they would have been forced to choose between worshipping G-d with prayer or worshipping pagan gods with sacrifices, they would have chosen the latter. Thus, G-d conceded to them their need to use sacrifices, but demanded that they be brought to G-d and brought in a way which did not lead to idolatry.
The question we should really be asking ourselves is this: do we wish to remain at a lower level of worship? Maimonides sought for a higher philosophical, a more sophisticated form of worship; not indebted to physicality in a mode where adherence requires the physical, primitive, delight in the enjoyment of sacrifice in which G-d loathes.
”To what purpose is the multitude of your sacrifices unto me? says the L-rd” (Isaiah 1:11). Jeremiah 7:22–23 agrees: “For I (G-d) spoke not unto your fathers nor commanded them in the day that I brought them out of the land of Egypt concerning burnt offerings or sacrifice. But this thing I commanded them, saying, ‘Obey My voice.’”
“I am full of the burnt offerings of bullocks, or of lambs or of he-goats… bring no more vain oblations… Your new moon and your appointed feats my soul hates;… and when you spread fourth your hands, I will hide my eyes from you; yes, when you make many prayers, I will not hear; your hands are full of blood. “ (Isaiah 1:11-16).
I hate, I despise your feats, and I will take no delight in your solemn assemblies. Though you offer me burnt offerings and your meal offerings, I will not accept them; neither will I regard the peace-offerings of your fat beast. Take you away from me the noise of your song; and let Me not hear the melody of your psalteries. But let justice well up as waters, and righteousness as a mighty stream. (Amos 5:21-4).
“To do charity and justice is more acceptable to the L-rd than sacrifice” (Proverbs 21:3).
"I desire mercy, not sacrifice." (Hosea 6:6).
The point is not to be missed: G-d does not desire sacrifices and Maimonides quotes the prophets for support.4
 From the “The Jewish Declaration on Nature,” from “The Assisi Declarations,” in Basilica of Saint Francis of Assisi (29 September 1986)
 See his essay here
 All biblical quotes from Richard H. Schwartz book Judaism and Vegetarianism
4 This is an excellent essay by Rabbi Shlomo Nachman where he quotes additionally biblical verses showing that G-d does not need nor want sacrifices.