It does have a low oral BA but as you say so do many other drugs. As long as you adjust the dose accordingly to make up for the low BA it makes no difference.
I fucking love a bottle of Oramorph. Even sipping a small amount gives me a nice high. Great as an actual painkiller too. There's a reason it's the gold standard by which all other opiates are compared.
Never had XR tablets so can't comment specifically on those.
But as others have said, people who hate on it are usually oxy or heroin addicts with huge tolerances. For them oral morphine does nothing because they're used to smack that may very well be cut with fent.
I also notice it's usually Americans who hate on oral morphine, probably because they have so much fent going around, and even if they stick to legit pharma oxy is what they use over there and obviously that's gonna bump your tolerance up enough you won't feel much from oral morphine.
But even British smackheads have love for the Oramorph in my experience. Example I am matey with a local beggar who is a heroin addict, I once told him I got Oramorph and he was saying oh that's good stuff but be careful it's strong etc. Another bloke I knew, wasn't a beggar or anything but was a bit dodgy and knew a few dealers who sold H, he told me be careful not only because it's strong but also because "proper drug addicts will come after you for it." He kept emphasising that to me, that "proper drug addicts" love the stuff.
But I mention oxy and usually the response is "what's that?"
TL;DR: Never heard any hate for oral morphine IRL at all, in fact I've only heard praise, only come across hate for it online when it's Americans with huge tolerances posting.