Brandur, this is indeed very actual topic (and will be even more with the rise of APIs).

As with everything, the issue is twofold. In the case of Heroku and your user-base it is reasonable to expect your users are closer-to-wire than an iOS guy hacking in Cocoa Touch.

From your point I can't agree more. A well designed HTTP APIs goes a long way here. Putting a Cocoa Touch developer's hat on and I can't be bothered learning HTTP, checking all the possible responses, handling redirects and errors when the only thing I need is to just fire a single Mixpanel track event...

Sort of C/C++ vs. let's say a Ruby. Assembler anyone? Stay on the metal or develop (and crash:) faster with some trade-offs.

Anyways, good stuff. Important bringing it on the table!