Re: "Jagex did not say exactly how Brexit will up its costs"
Unfortunately it's rather more complicated than that.
No, it really isn't. The decision has been taken, it is incumbent on us all to make sure we get the best outcome from it, whether we like it or not. It's really just like after an election, you have to work to make the best of the result, because nothing else is constructive. What an old manager of mine used to call "disagree and commit".
The brexit referendum: was only advisory
So do you think people would have been happy if Cameron had said "Oh, you want to leave? Well, we're not going to, forget I asked". You don't hold referendums if you're going to ignore a result you don't like. If you just want advice, hire a polling company, their results you can ignore.
omitted a large number of otherwise normal UK voters
"otherwise normal"? What does that mean, and how were such people omitted? Everyone on the electoral register was entitled to vote.
and was a straight yes/no question where the issues were rather more complicated.
No, the issue was a simple yes/no, stay or leave. All the complicated issues are part of the negotiations and you can't hold a referendum on them because they have to be negotiated. It was, of course, up to the people who voted to look at the potential issues and decide how to vote based on them. Some did, some probably didn't, much like in an election.