People who would, of course, be shocked when they rock up and discover that they get a pittance that barely covers existance in the UK, while being constantly badgered to either get a job, or supply convincing evidence that they're looking for one.
Including a young quadruple amputee, already known as such to the authorities, who was asked to attend a meeting in person to reassess his DLA. An extreme case, to be sure, but other cases surface regularly and seemingly more frequently as the administration of the UK's benefits system is increasingly privatised.
Meanwhile, if foreign nationals get the levels of child benefit applicable in their home country it opens up the real possibility that they will get more than Brits living in the UK. After all, some EU countries have more generous benefits than the UK.
I agree with H'ethetheth here - the whole benefits caboodle is pandering to the xenophobe vote, which is why we're having the bloody referendum in the first place.
The UK has one of the most tight-fisted benefits systems in Europe.