Law =/= morality. Everyone has the right to free speech regardless of the law. It's a basic human right. If people don't like what you are saying, they tend to give you a derogatory label in an effort to make what you are saying less credible. Sensible people will listen to your points and make an informed judgement. Half of the rest will scream racist/whatever and the other half will believe it because "I'd never agree with a racist".
Nobody is saying people are lobbying to remove peoples right to free speech, they are doing it by giving derogatory labels to make their argument weaker. At least explain why uncontrolled immigration is a benefit when a country is struggling to cope with the increasing population. Did you know that 13.5 Million UK citizens are classed as living in poverty (just under 1/3 of the population)? How is uncontrolled immigration helping exactly?
Addressing a the problem of unchecked immigration is not frowned upon. Approaching it in a constructive way is
vital.
Addressing it in this fashion:
Is, in fact, a scumbag thing to do and while there may be a "right to free speech" to allow you to express yourself as such, you have no right to defense from sensible people who call you out for your idiotic behavior.