The UKBA must refuse 30% of settlement visa applicants

Hardly surprising.
The statistics don't support anywhere near 30% refusal rate. Closer to 10% max overall.
Additionally that kind of target would not sit at all well with the UKBA business plan. Especially their tactic to both reduce the number of appeals and to also reduce the number of appeals that they lose.

On controling eeu imigration ALL the countries do that already by the mechanism of the citizen needing to be a "qualified person " after 3 months in that country after which time you either have to be retired, in employment or have indipendant means

EU directives allow removal if after 3 months you do not meet requirements. But who does that?
Unfortunately no-one knows who you are, where you are or how how long you've been wherever you are.

The ECJ ruling has now been incorporated into domestic legislation as regulation 9 of the Immigration (European Economic Area) Regulations 2006.
These provisions are not confined to just spouses and civil partners but also to 'family members of a United Kingdom national'. Family members in the European context are defined by regulation 7 of the EEA regulations.

By the way, in the case of Surinder Singh, they both worked in Germany between 1982 and 1985 when they first came to UK so their employment was actually quite long.
It's an interesting case and worth reviewing.

Always difficult to predict anything these days with change always on the horizon.

Let's say that UK will NOT make changes to their relationship with the EU on the basic treaties then the freedom of movement directives will remain applicable.

The HO/UKBA can always take a 'local' view of the directives and instigate operational restrictions.
Probably unfair to use the term 'clamp down' on EEA immigration routes, but certainly putting in some extra demands.

In fact, as I've mentioned somewhere else in this thread the UKBA are now really pushing hard on their Family Permit scheme.
A Family Permit is in reallity a UK entry visa.
Make no mistake, UK is not the only EU member with intentions to 'tighten' up on free movement especially in connection with security.

The UK's position is that of not interpreting the EU Directive as providing for the mutual recognition of residence cards between EU Member States.
UK has concerns about the security of residence cards.

The UKBA has never stated that it's compulsory for family members to have an EEA Family Permit before travelling to the UK, but in cases where there is no Family Permit the UKBA officers may require to seedocumented evidence presented by passengers that they are entitled to be admitted as a family member.
Nevertheless, some refusals have been made and a number of complaints lodged resulting in both an Article 258 letter and a subsequent 'Reasoned opinion' being issued by the EU Commission.

The next level of escalation (in the event of no agreement by UK) would be that the EU Commission could have the case referred to the ECJ.
Only the ECJ ruling can be considered legally binding on member states.
The UK government would never consider operating illegally as an EU member.