I'm surprised that the ad sevices aren't smarter. Wait until on wifi, cache a bunch of ads, share those ads amongst all the apps that use your service. Is this feasible?
[edit] for advertizement driven software. Energy efficiency is something which goes to the bottom line of handset manufacturers. That this research comes from Microsoft, not Google, shows how different the incentives in regards to energy management are for the two companies' mobile OS's.[/edit]
[edit 2]It also illustrates the problem of the commons inherent in the app model. Lots of contact with the ad server is great for each app and poor for overall energy efficiency.[/edit 2]
Whether the ad companies are measuring and paying attention to this is a different matter.
Otherwise... it's just another reason to learn smali.
But seeing it 100.000 times is NOT going to make me purchase it.
I imagine that the harder part is grabbing the right ads so that you have something relevant to show. There's also some concern about leaking ad information, but I'm not sure how much advertisers care about that.
That alone would require it to be OS-level, at least on iOS (AFAIK).
On Android this is obviously much easier. Just use a content provider as I mentioned above.