> abstracted representation
Yes, the EU representation is quite distant. The UK has an unelected upper house.
> Foreign authoritative bureaucracies?
This isn't great, but at least the EU one is elected. The alternative in all the other trade deals is unelected. Hence all the opposition to things like TTIP, and earlier complaints about GATT etc.
Fundamentally, voting against the EU doesn't make it go away. Some sort of framework always needs to exist to make agreements with other European countries. If the EU didn't exist, it would probably be necessary to invent it.
Hence the Norway/Switzerland situation: not in the EU, has to follow EU rules without having a vote on them.
> legitimate concerns
Here's the thing: hardly anyone talks about those anymore. Brexit has been absolutely dominated by antipathy towards immigrants, both EU and non-EU (despite this not being anything to do with the EU). There's no way to "unwind" EU immigration without ripping families apart.
(I was a Euroskeptic about the treatment of Greece, for example. But ultimately Greece realised that however bad a situation it was in, crashing out would be worse. The same applies to the UK, with "Tory Syriza" running it)