Rabbi Joshua Berman defended the importance of offering sacrifices in previous Temples as well as in the future Beit Hamikdash.
This claim is based on a Pasuk in בראשית that says פרו ורבו, Be fruitful and multiply and rule over all of the animals. Man’s dominion over the world was part of the Divine plan. Man was also commanded to emulate the ways of Hashem. He did this by acting with kindness and compassion.
The offering of animal sacrifices to G-d was meant to drive home the point that although one can act in a G-d like manner, he was still subservient to Hashem. Thus, the animal that man had dominion over, became the vehicle to show G-d’s ultimate dominion.
Rabbi Berman claims that there is not a single source in biblical or Talmudic writings that advocate or praises vegetarians. He says that those who protest the use of animals for sacrifices, are animal rights activists.
Instead of emulating G-d and using the animal as a symbol to get closer to Him, the animal rights people glorify the animal because they themselves behave in a more animal-like manner than a G-d-like manner.
I realize all of this is debatable, but it does give us food for thought.