It doesn't mean it will be able to experience pain, or feel pleasure, or love.
Why not?
Simulating an earthquake inside a supercomputer doesn't cause actual tremors inside the server room. Simulating a blizzard doesn't produce actual snow. And I have yet to hear a good reason why simulating a brain would produce actual consciousness.
But if you simulated that roach brain (or a human brain, or an entire human body) in that earthquake simulation, how would the simulated entity tell what is real (the still of the server room) from what is simulated (the tremors) ? You're still missing the point - the simulation doesn't impact reality outside the simulation, it's just that anything inside the simulation will have no way to tell that the simulation isn't reality.
If a brain is just a computer, I have yet to hear from you a good reason why simulating a brain wouldn't produce consciousness. The only reason (so far as I can see, correct me if I've missed something) a sufficiently detailed simulation of my brain wouldn't be conscious is if you asset the existence of some immaterial component like a soul that is responsible for consciousness. No evidence points to that being the case, though.