It's interesting though, the first mot pass rate for new cars at 3 years old is around 80% at second MOT The rate is still around 80% where as a 10 year old car which gets an MOT every year the pass rate it's only once you get to about 7 years old does that pass rate drop to 70% (55% by 10 years) so this will be their justification for increasing the time till first MOT, it might actually improve things as people who keep their cars passed 3 years old won't be reliant on the MOT being a health check and may actually get there cars looked at and serviced.
Our mini just turned 3 and came with an all inclusive service package, every time it went in for a service they did a full health check and identified anything that needed attention like worn tyres, and they called it in for a check just before the MOT was due to identify anything that needed doing before its MOT that would prevent it passing. These service packages are becoming more common so I would expect this practice to become fairly standard with new cars in the future