16gb should be fine if you run your phone lean and mean - music in the cloud, back up / delete photos and videos from time to time, no big games.
with ios9 being smaller and the new app slimming feature this will work even better. the only problem that bugged me often was that bloated "other" space - on my old 8gb iphone 4 i regularly had to delete photos and apps, just to keep the few hundred mbs of fee space it needed to operate fine. i had to reset the whole phone about every year because of some apps temp-files getting bigger and bigger (probably mail, facebook, ...). it's the same with my ipad (that's where i store the big apps and games - i fikled abot 50 of that 64 gb in the first day - without any music & videos), but on a 64gb device, it takes much longer for that 5gb of dead data to become an annoyance - at least, i'd welcome some memory management/more info there.
and yes, they are being greedy by saving 2-4$ for that extra 16gb. it just wouldn't matter that much, if the software ran better.