It's not just Eastern Europeans who are leaving - it's people from Germany, Sweden, Denmark, France, Netherlands and so on too.
The interesting thing is that the people who have come here to the UK have taken jobs that Brits do not want or can't do. Jobs that require specific language skills for example. And fruit picking, factory work and basic hospitality jobs. The vast majority of EU nationals working in the UK are in high-skilled jobs.
These jobs have always been available to British people - but if the British businesses cannot find anyone in the UK to take those jobs, then what are those businesses to do?
And if we're going down the "TOO MANY" route, then it's worth keeping in mind that EU immigration levels are lower than non-EU immigration levels. But as politicians have said, the immigration levels are unlikely to change much because of Brexit - and if mass immigration is such a massive issue, why have the UK governments not done anything to control it? It's perfectly possible to control, even while in the EU.
What is likely to happen is that the UK will still keep the door open because British business need foreign workers to take the available jobs, but the British people who want to move to European countries will find it far more difficult in the future.
But it is simply not fair to blame people who are coming here to work - they are coming here because they are fully entitled to do it, and because the jobs are available. If they didn't come here to take the jobs, the British companies would struggle to find people to take the jobs, and it would impact the companies negatively.