Also - 'the mobile web' did not exist before the iPhone popped up. Now you have a blazing-fast mobile webkit used in Android, iOS and on more recent Blackberries, and have a quite decent mobile IE on windows phone. Each generation of mobile OS, the mobile browser performance improves massively, adding more and more features with every generation. But somehow they are blocking 'the open mobile web'?
Also - a browser is not the only 'web application'. You already have mail, RSS readers, calendar apps, twitter clients, ... in whatever form, webapp, native desktop app or mobile apps - they all exist. They're all using 'the open web'. I think inter-operability is more important than "it has to be html5". The open web is in my opinion: open API's and data format. And that is exactly what we have, a large amount of mobile apps are just a native more intelligent client for some web API or content for which a website is also available. Twitter, Facebook, Reddit apps, Kickstarter, ... all have 'native' apps - does that mean it's less open than using a web-browser? No - it's just optimized for mobile use, something that is very hard to do with pure html5. REST/JSON api's have taken over the open web. Native or web-apps are just front-ends for these api's - that's the direction it's moving in.
I don't see the problem really, web-browsing still is one of the killer apps of a mobile device - tablet or phone, and that's something neither Google, Apple, Microsoft, or any other large corporation will ever limit. Yes some apps are rejected for whatever reason, but there is competition to choose from if one of iOS, Android, Windows Phone, Firefox OS or Mobile Ubuntu makes choices in their rejections that conflict with your personal beliefs.
Both Android and iOS are built around promoting apps. The web is a second class citizen.
On iOS I would go as far as to say a third class citizen, since Apple are blocking the fast Javascript engine in native apps. This makes the idea of having an app as a simple web-wrapper much harder to accomplish.
But if the systems were actually optimized for open web, then content producers could build 1 web-app, that could have important logic and graphic stored offline in an app container, while still being just as functional via direct web access.
This could work great for 90% of all the apps that are basically just glorified websites.
This of course is the main mission of FirefoxOS.