With large expenditure on a phone, that you are lead to believe you cannot easily return if you don't like it, people want to play it safe. There are many Sony Xperia phones.
Benchmarks really don't matter to the modern world - they never mattered to the people who really wanted to use Smartphones: everybody!
The iPhone3G revolutionised the way in which people interact with the handset. It's the interface that matters, 100%. I can switch between Mac OSX and Windows 7 (and below) with no issue. People find themselves drawn to what they trust, and that is simplicity, seemingly the iPhone, or up to date functionality, which is why Samsung are doing so well.
But £400 on a risky Sony purchase come this January? I doubt most people will go for it. You earn credibility over many years. Nokia have sunk due to some bad software decisions, but also a cumbersome O/S that everybody still mentions - Symbian was never suited to 2012. The only place rubbish phones really sell in large numbers is China, due to consumer cost limitations.
I've tried a few Sony Xperia phones and they were generally broken or damaged in the shops, suggesting robust, rugged build quality is not at the top of Sony's mobile phone agenda. I do hope for for something truly amazing to appear, but I think people have been so heavily told "THIS PHONE changes everything!!! Yea, this new one, just out! BUY!"
People now say 'no', due to lessons learned in which phones they've bought every 18 months are actually pretty crap.