Back to the future with mobile devices

The mobile device application market is a lot like the software industry of 20 years ago. Twenty years ago we had a lot of operating systems running on a bunch of different hardware platforms. If you wanted to develop an application you needed to develop it for each operating system and port it to each platform. The only way an end user had access to an application is if they installed it on their computer. We then moved into the modern, web era of computing. Life become so much easier for everyone. Software companies can now develop new applications once, put them on the web, and everyone has access. They no longer are porting to different operating systems and hardware environment. End users love the easy accessibility of using applications when they needed them without having to bother with downloading and installing software. This all worked well until we started moving to the newest computing frontier, mobile devices. Now we are back to the future, operating specific applications that need to be developed and ported to each device, and downloaded and installed by the end user? For mobile devices, why have we moved away from the beauty, elegance, and simplicity of web sites and web applications?