I suppose my only counter left would be "is the UK market alone worth the complexity?" Having split off from Europe, and in-fighting among ourselves to the point where we may see the UK itself splitting up again in the next decade. Is it really worth adding additional complexity for a comparatively small market when companies could simply target the continent of Europe as a single market, regardless of EU membership, and probably reach a similar audience with a similar conversion rate.
I'm probably being overly cynical and only time will tell, but I just don't feel the UK alone commands the importance to have things its own way, so to me being lumped in with the EU as the lowest common denominator seems inevitable.