In my eyes (and maybe this is unreasonable of me, anyone else?), you lose credibility when you state, as fact, your own opinions that you know other people disagree on.You begin your comment by saying "You make one good point…" Is that a fact? No. Did you state it as a fact? Yes, in that you stated it without qualifiers. Does that mean you have no credibility? Of course not, come on.
For the rest of it, let's rephrase your own logic a bit: "I don't know if sending people to the back of the bus is wrong, but I care little enough that I probably won't decide for the foreseeable future" would be a pretty weak argument against declaring segregation unethical.
It hinges around the idea of whether or not you're hurting people. You started your original comment by saying that "clearly unethical" is a debatable point, but then you tried to draw an equivalence between piracy and a three more victimless acts. You then say "ethics don't matter" and follow that up with "I don't hurt people." I'm saying you do hurt people. It's debatable, but you dismiss debate of it by trying to argue that ethics don't matter and you're not going to think about it. That's not a good counter an assertion that piracy is unethical.
(As a side note, the Stanford Experiment and related studies suggest that both of us would beat and murder women if it were socially acceptable. Creepy stuff that, which is one of the reasons why I think it's important not to tie "ethical" too closely to "socially acceptable." It's also why your notion that "ethics don't matter, I don't really have to think about it" upsets me, perhaps more than it should.)