I don't know how well the DS remakes sold, but given the installed base of iOS and Android devices, it's no doubt much more financially viable to dump a $20 quick-and-dirty port that will probably sell several hundred thousand times onto those platforms and bank on nostalgia and the Final Fantasy name (who else can get away with selling games for >$20 in the App Store?) than it is to remake V and VI from scratch and sell 30 or 40 thousand copies for $40 on 3DS / Vita to nerds like us.
Our dreams of a remade FFVI fade, like tears in the rain.
How much data can we pull together to actually test this. IIRC FF3 for DS sold over a million in Japan alone, and the Dragon Quest games have done similar or more. That is a LOT of revenue. Keeping in mind that the handheld console versions need only prove themselves worth the effort in terms of ROI. Just because one makes less money than the other, doesn't mean its not worth the time.