On the dead simple end where you just want essentially a blog with ads, it's easy. On the not-so-simple end, where you want to build an application you can charge money for, the app store model is very straightforward. You don't have to make any decisions about servers or hosts, do any sysadmin work, worry about traffic spikes and scalability, and your cash outlays (aside from development time) are all upfront and totally predictable. Similarly, payment processing is already there and handled for you. And lastly, you don't have to worry about SEO or distribution channels because you don't have a choice in the matter.
It's easier to put up a web page somewhere than to build an app for the app store . . . but for a large number of people building an app for the app store is much simpler than putting up a web application. And that, I think, is a big reason why the app store exploded.
I had a few friends in high school that made decent money making websites for eg a local car dealership. It was easy because it's just HTML.
Despite stuff what HTML is made for (like static websites), almost everything else is much easier to develop in ObjC with Cocoa (in some IDE like Xcode).
Let's take a simple 2D top-down game (like Legend of Zelda) as an example, with an inbuilt level editor and some way to save/load games on/from your local disk (or for the web equivalent: somewhere in some database).
That is quite easy to do with ObjC. I, for example, started to learn coding with Visual Basic many years ago, and that example was my second project (after a few weeks of coding -- never ever coded before). (Ofc VB is way different than ObjC but they are similarly easy to handle.) The point is, leave some newbie alone with Xcode and he will manage to implement something like this (without much extra documentation because most stuff is straight forward).
Now, let's leave some newbie alone to implement that in HTML + JS + whatever serverside language he prefers. He maybe will fail already to setup the web server.
Also, learning a new language or library that's different enough from what you know that it takes more than a few hours to be comfortable (generally) makes you a better programmer.
Sorry, I do realize you were mostly trying to pile onto the IPhone cost tally, but I'm always surprised to see other programmers imply that learning new things is inherently hard and undesirable.
Now your only barrier to entry is a Mac mini and an iPod touch. Both of which can be had for less than $1,000 in 2010 dollars. The real barrier of entry is about 25% of the price we paid in the 1980s.
$997 is a lot more than 25% of $2000
As compared to a computer, which pretty much everyone had by 1998. Also iPhone programming is way harder than HTML. I had a mandatory high school class that taught HTML.
Maybe I'm underestimating how many people are jumping on this, but my intuition is it can't be as many as were jumping on web. Twitter/social media marketing however... :P