You can blame David Cameron's government who swore to get net migration to the UK down to less than 100,000 per year from over 300,000.
They couldn't do anything about EU migration, so first they tightened the rules for work visas and student visas and then they targeted settlement visas. Theresa May was Home Secretary at the time and brought in the tough rules in July 2012.
EEA citizens wanting to come to the UK to work, was never a problem and net migration to the UK remained at 50,000 a year for decades.
In fact workers from the EU could ask for ILR as soon as they arrived if they were working in the UK. They could even asked to be stamped in "ILR" at the border when they arrived to work in the UK. If they didn't want ILR, any child they had that was born in the UK, was always born British if they had an EU citizen parent who was working in the UK. Even with that open door for any hard workers from the EU, UK net migration remained at 50,000 a year.
However that all stopped for EU citizens in 2000. Blair and his Labour party had been voted in to govern the UK. No grandfathering in either as even those EU workers that arrived before that date, has now lost their chance for ILR. No more of therir child being born British if they were working in the UK, which is a bizare situation as they could have a child born in the UK before 2000 that was born British and child born after that date now not born British.
Then in about 2002/3 came in the invention that Blair called a vote winner for Labour, a welfare payment called "Tax Credits". This welfare payment meant there was now no need for parents to work anymore or to work more than 20 hours a week between them if they didn't want to (that 20 hours a week gave them more of money from their Tax Credits benefit). That benefit money for the children, was given to their parents to spend. The Labour Minister in charge of child welfare, resigned. Net migration to the UK then went to the hundreds of thousands every year.
Easy UK visas were then created for low sklilled non-EEA citizens too and the EEA citizens could claim Tax Credits and all other benefits as soon as they arrived and they didn't have to ever work. We even had a situation where International students could have ILR after 10 years even if they didn't pass an exam. The clever students who firms wanted, had to have a Resident Labour Market Test. That RLMT requirement for international students that firms wanted, ended when Labour was removed from government.
In 2014 the MAC reported that in 2013, 6 billion pounds a year was being given to those who are a foreign national or who were a foregin national when they first applied for a NINo, just in that one welfare payment called Tax Credits alone.
