If you think about it objectively, there is nothing at all special about a human being. Humans are just biological robots running software on a dynamic finite state automata neural-net CPU (to the best of our knowledge). And there's nothing special about our CPU apart from the fact that a human engineer wouldn't have designed it that way (it's way too complicated to understand and debug, on the other hand, it can sometimes still function even if we remove half of it).
Since there is nothing special about our hardware, it stands to reason that there's nothing special about our software. By "nothing special" I don't mean to imply that it's not complex, only that it is all in our brain - it's just signals in a machine.
Given that complexity is the only difference between my mind and this Linux OS running on my laptop, it stands to reason that it's not impossible for hardware/software to be created that can experience emotions and pain the same way I am. (The corollary is that if it is impossible for a hardware/software to be created to experience emotion and pain then humans wouldn't be able to experience emotion and pain).
Thus, it's false to presume that robots cannot experience emotion and pain. While it is very highly unlikely that any robot we have today are capable of experiencing pain, that isn't true for the set of all possible computing machines (of which humans are arguably a part of).