Consequentialism is a front for evil. Every example ever relies on a model, not the real world, so you can slip in any assumptions to justify whatever you want.
Every ethical decision has a texture that's inseparable from our instincts and their significance within a larger ecology, a dimensionality not capturable by "utility" (which is only an axiom enfocing transitivity within a model, not some a-priori idea of "value".)
Good is the proliferation of life. To ignore instinct is to ignore information embedded in life that helped it proliferate.
Before anyone takes me out of context, this is not an injunction against the application of reason, it's a warning not to limit the application of reason to a tinkertoy approximation of reality.