The world was a much smaller place 240 years ago. You can't compare the two.
While the EU isn't perfect more effective change could have happened from within, slowly, without destabilizing the world economy, and emboldening Putin who undoubtedly is rubbing his hands with glee.
This was mostly about a bunch of old racists and xenophobes getting together and spouting a bunch of lies, Jeremy Corbyn more or less sabotaging the "remain" camp from within, and people not thinking that their vote would mean anything going out and voting in droves. To be fair, the majority of politicians in the UK have long been out of touch with their constituents, much like they are here.
I just don't get how you can think this is a great thing. The UK Pound dropped to its lowest value in 30 years. Stock markets across the world tanked. We're talking literally billions if not trillions of dollars wiped off the map. (I'm afraid to check my retirement account.) The UK that the leave camp fought hard to "make great" again is going to be cleaved in half. The United States had a lot of influence in the EU because of British membership. We're simply not close to France or Germany like we are with the UK.
Spain, Portugal, Greece, etc. are failing because of poor local economic choices, not ones mandated to them by the EU. Their policies were untenable and, really, they are only still around because of the EU. If they had been left to fail it's very likely that civil war would have broken out and some charismatic right leaning person could have seized power and blamed all of their problems on the ethnic minority du jour. Those are the folks that led the Brexit vote and those are the folks winning parliamentary seats in France and other places.
Europe has been at peace for 70 years largely because of the EU. As it falls apart do you think that it will remain that way?
Brexit was an incredibly ill-informed short sighted decision made fueled by racism, lies from the right, and dreams of a British empire that the elderly deluded themselves still existed after World War 2.