Why are there people that strongly oppose to physicalism and use anthropological arguments as if reason is more ontologically relevant (or may I say essential) than matter?

I think both "realms" do exists: the idealistic and the physical.
Ideas can interfer in physical, but only within the idealistic perspective. Still, the mind depends on a physical organ (brain) and a function organism to work, and they need chemical reactions to be alive, and it needs matter to exist.

Really i can't understand why is it so hard for many to just accept that reality, as we perceive, is essentially made of matter and all our decisions are made because of physical reactions on our brain.

But okay, keep on believing in that weak solipsism of yours while you take your brain stimulating substance called Ritalin.