Passport fraud was all in the news a day or so ago.
http://uk.reuters.com/article/domesticNews/idU KL208902520070321
It is estimated over 10,000 passports were issued last year to fraudsters.
This country has been so lax in the last 10 years in allowing in illegal immigrants, organized criminal gangs and so on that we now have thousands of people with UK passports who should not have them.
THAT is why you have to go for an interview.
Sugest you moan to Tony Blair for allowing so many undesirable people into this country.