The size isn't really an issue - if the big chips were 0.05" pitch QFPs, I'd imagine they'd pop back onto the radar (even if the typical power use would remain discouraging).  He mostly abhors BGAs; especially fine pitch umpteendozen/hundred ball BGAs.  This is a CSP which typically means there'll be a BGA or LGA style physical interface to the actual chip, in which case the pitch/ball count is what matters the most.  Even at 0.5mm pitch and unpopulated areas, that's a lot of balls, many of which difficult to inspect.  Would be unnecessary hit/miss soldering jobs, or having to choose to outsource board population for just that part.