Your first point is so valid. Having created a webapp for the iPhone myself there really are few places I can go to put my webapp on a stage that anyone cares about. If someone knows of any I honestly would love to know where they are.
It's far better to build up a real sustainable following yourself based on real merits. The app store is full of gimicky one time apps people will use once to show their friends, then never use again :/
That said, I've been wanting to write a free guide to SEO aimed at HN-like companies, because I think its important. However, the response from HackerNews to anything involving SEO is so harsh, I've felt it would be a waste of my time. If that's not the case, please let me know.
Almost every successful startup you've heard of which publishes lots of content has an SEO strategy. Slideshare, Scribd (good golly were they aggressive with it -- good thing they got big before they got smacked), Yelp, etc etc.
As a distribution outlet, nothing (yet) can compete with the app store.
The client see's it as a "iPhone app" you can host/sell it in the store, but it's really just a web app.
(Maybe there's a restriction on this, but I can't see why there would be...)
So this doesn't solve the problem.