Once you buy an app, you can delete it from your device and re download it at any time for free. So, you do not NEED to store EVERY app you EVER buy.
This is a good point but overlooks two things:
1. People don't buy smartphones because they are dying to spend more of their time managing smartphone storage space. For most people, it's better to overbuy storage than underbuy it and spend much more time choosing which apps you'll be in the mood to use today ... I personally have "fixed" this probably by only buying and DLing apps I will actually use regularly
2. As you yourself point out, apps (with few exceptions) don't really take up much space. There's a few games (I'm looking at you, Infinity Blade series!) that do, but non-game apps actually, by and large, take up very little space.
Movies are not even that great on a phone. Get a iPad.
I'm with you on this, though I'd say most standard TV shows* look just fine on an iPhone and with the headphones on are really quite immersive.
*by this I mean sitcoms, normal shows ... big-budget extravaganzas and HD stuff looks way better on an iPad (well, as does everything, but you know what I mean).
16gb is really all one needs. Filling up 64gb on a phone is a little crazy.
With a little bit of discipline (mostly deleting podcasts and videos once you've watched them and swapping out with new ones) I'm with you.