Agreed but there is little short-term evidence to suggest that there are/ will be any benefits to Brexit, in fact, the opposite https://www.ft.com/content/c6ee4ce2-95b3-4d92-858f-c50566529b5e
Likewise there is little, if any, evidence to suggest that the current UK government is any less incompetent than the EU authorities.
Any evidence/ sources that provide projections to support this wishful thinking?
That there are federalists in Brussels and the EU is undeniable, but unless the individual member states vote for a federal Europe (which they won't) then it will not happen.
Unelected technocrats in Brussels - I assume that you mean the Commission? - do not pass laws. EU legislation is passed by the European Council - which is comprised of the 27 member states' heads of government - and the European parliament, whose members are directly elected by the voters in EU member states.
In a similar way to the unelected mandarins in Whitehall, the unelected technocrats in Brussels take their policy direction from their political masters (the UK government and the European Council respectively).
One added value for member states is that they can direct the Commission to work on policy areas where they may lack the necessary time, resources or expertise to do so themselves.
Between 1999 and 2016, the UK was forced to enact +/-2% of EU legislation with which it disagreed.
https://fullfact.org/europe/eu-facts-behind-claims-uk-influence/
I don't believe that all the economic, political and social chaos caused by Brexit is worth it in order to reclaim 2% of sovereignty but clearly others disagree.