I don't see what's the big deal with carbon deposits on DI engines.... yeah it sucks; but simple to solve/maintain. You do lose some power in the long run, but with how aggressive/reactive the FA ECU is with timing, I doubt it's a reliability issue unless you let it go way out of hand.
My Subaru dealer has the top end cleaning as a regular maintenance item for the 100,000km service (They call it 'Type C' service). So it shouldnt go that far out of hand if you're following manufacturer's recommendations....
All manufacturers are going for more short-term stats and numbers rather than long-term reliability.