Yes, we don't have non-white politicians. Apart from the Mayor of London, various cabinet and shadow cabinet ministers
The main issue was actually democracy and always has been - long before the various migration crises. The EU is a profoundly anti-democratic organisation that rules by technocratic diktat and whose explicit (it's actually written on the wall in Strasbourg) intention is the dismantling of the nation state in favour of a European superstate ruled from Brussels. Its parliament is an unrepresentative rubber-stamping body rendered impotent by its sheer diversity, which means it can never provide meaningful opposition to the unelected, unaccountable Commission, which is the only body that can make law. Nobody who calls themselves a democrat can possibly defend that situation and no American would dream of allowing themselves to be governed in that way, so please spare me the finger wagging.
'So why leave? Why not try and reform it?', I hear you ask. That is literally what we have been trying to do for 40-odd years. No dice. The goal of 'ever-closer union' is paramount and the Brussels juggernaut keeps on rolling. When Cameron went to the EU before the referendum trying to get some concessions that might help him win it, he got nothing because the EU is simply too inflexible even when it meant the possibility of losing a key member state and its second biggest net contributor. As a result, the referendum was lost - because the EU isn't going to change.
Are there concerns about immigration? Of course. And they're pretty justified. If you think mass immigration from the Middle East is a good plan, look at what's happening in Germany and Sweden, who have let huge numbers in. Does looking at that and saying 'no thanks' make one a racist? Equally, there's the migration from within the EU, which allowed a massive influx of people from Eastern Europe into the country a few years back. That has been positive for the likes of me, who can now get cheap plumbers, cleaners and decorators, but not so much for people lower down the scale who feel their chances of employment or access to public services are being negatively affected by this influx. Does resenting that make them racist?
Be very careful with the accusation of racism. Once you apply it to any issue that might even tangentially relate to race, it starts to lose its meaning.