@LucidSDreamr no one is saying that using heroin (or any other opioid, or any other drug for that matter) is entirely without
risk, even if we separate out the issue of legality. If you regularly (ab)use ANY drug, there are risks associated with that behavior.
I mention this because I get the impression, when reading some of your posts, that the implication is, people are saying that there are no risks associated with regular usage of narcotics etc, and that everyone should have a devil-may-care, let's-all-go-do-drugs! attitude, but that's emphatically NOT what I'm saying. Just to be clear on that point.
With that being said, I do think that the class of drugs that heroin belongs to is relatively soft on the body, with relatively few side effects. The risks you mentioned associated with the consistent usage of opioid drugs, like your sexuality going to sleep on you, could just as easily be said of substances which are legal and available to consumers today, like alcohol or antidepressants/other psychiatric medication. You can take the brains of two people, one a ride-or-die degenerate junkie who lived and died by the needle and couldn't go a single day without slamming a million bags of dope, and the other a person who had never even used a single recreational drug in their entire life, and there's a good chance that you wouldn't be able to tell the difference between the two. I've often thought that the physiological basis for opioid addiction is overstated, both by people who use these drugs (i.e., "I can't possibly stop using these drugs because then I'll be 'sick'") and those on the outside (addiction treatment resources etc.)
The point about being unable to feel pleasure or happiness anymore because you've nuked your brain with too many drugs...the obvious solution to such a problem, which went unmentioned, is to stop using drugs for a period of time. When a particular drug loses its effect, that's one of two possible options...the other option is to increase your dose and keep going, but that's unsustainable in the long term. It reminds me of a topic I saw on this website, which went along the lines of, "if you could choose to be high all the time, what drug would you choose?" To me the idea of being "high all the time" is a ridiculous and nonsensical notion, because you only get "high" when there's a LOW (or at least a "normal") to compare it to. If you're high all the time then being high is your new baseline state of existence, and the whole question becomes meaningless. That's why tolerance breaks are important, and why every single drug user on planet earth can be divided into 2 camps once this inevitable event happens (i.e., you take the drug you normally enjoy, at the dose your normally enjoy, but it fails to have the desired effect): you either 1) pump the breaks on your usage a bit, or 2) escalate your usage. They're not absolute categories...just because you're able to control your usage at one time in your life doesn't mean that that'll always be the case, but that (or the fact, as I mentioned, that ALL substances possess risks, and there is no "free lunch" when it comes to drugs) doesn't mean that people should be denied the freedom associated with being able to choose what they ingest into their own bodies
And, finally, I don't think that using an opioid drug, in a legalized permissive environment, will necessarily lead you to IV drug usage, anymore than having a beer will inevitably lead you to waking up in the morning and pounding down three shots of Jack Daniels just to feel normal.