I have read a few forums posts in relation to deploying RDS 2012 RemoteApps to clients, and I too am disappointed there is no longer an option for deployment using an MSI package. Our existing mature 2008R2 RDS infrastructure allow for this to happen - and I deploy several RemoteApps using a GPO to distribute the application to our VMWare View Windows 7 linked clones.
I decided to trial RDS2012 and decided that, as MSI deployment is no longer an option, I would try using the "Distribute using Web Feed URL" option. Unfortunately I cant find a way to push this option out via GPO to Windows 7 clients.
Any advice would be welcome.