Hmm, I guess maybe you did somehow, because:
even on a net-locked or SIM-locked device you can install almost any application you want to.
You just cannot replace the device's ROM or use a different provider (net-lock) or SIM card (SIM-lock).
And the times of very limited WAP content versus free internet access sold as "mobile web" are already gone, anyway.
But basically you are right, you can already use applications with online services (be it weather data, RSS newsfeeds, stock quotes, etc).
As I'd see it, this mostly is a "mobile to online" approach, and there shouldn't be much (if any) limitation of that from the network provider.
Major changes and extended options / functionalities etc would have to be expected with kind of an "online to mobile" approach, i.e. content / services already available in the web.
Quite a few of the mobile network providers tend to restrict content access as they want to draw a significant portion of the profit from the content and not only from the network service.
As far as I understand it, this actually should be what the report/study targets.
Also, it should probably not especially apply to Windows Mobile powered devices as they actually already by default provide more or less unlimited functionalities and web access.
It'll still be much more different with even more provider branded devices, where you are almost completely limited to what the provider has already implemented (including restricted content access etc).
But also, consider tariff structure: current mobile data tariffs still are too expensive for POP3 email, RSS feeds, unlimited web browsing and therefore also significantly limit user experience.
If there are no restrictions through your provider (and you have a mobile data flat rate), feel free to already get all of the available web content - maybe you just require to install some third party software on your device
or soon benefit from something like Spb Online Shell services.