Practical IPFS image hosting looks an awful lot like image hosting without IPFS. Most of your traffic's gonna be through gateways, not over IPFS proper. You've still gotta have always-on servers pinning (storing) everything for reliability. There also doesn't seem to be a good way to make mobile devices—most of the clients out there—useful parts of the distributed network.

HN throws IPFS around a lot as if it's free storage + free bandwidth. But as you point out, you still must run an origin server. At which point it's just a slower, crappier CDN where you stand up your other CDN nodes yourself. Your content doesn't just magically spread to random nodes once you broadcast it.