This is useless if all the SEs don't adopt it.
If MS can't get the others to index APPs using the same mechanisms then it's a waste of time.
On the flip side, perhaps if Bing can get some serious new differentiating factors that you can only get on Bing, perhaps those kinds of capabilities will get more people searching with Bing. Perhaps the thinking is because of the high volume of people searching for apps daily that they can take a big bite out of app searches using this technology.
Problem is people using Android or iOS predominantly search using the Google or Apple store, therefore they'll never see these results in Bing in the first place. If they knew Bing did app search perhaps people would use it but most of the web doesn't have a clue beyond email, FB and twitter they're mostly web illiterate.
By the time Bing makes is a success, Google will add it the next week and wipe out all their efforts.
So that leads me full circle back to why bother.
Microsoft IP addresses openly mock my website
While your comment is off topic and has nothing at all to do with indexing apps, I'll address it just because I think it brings up an easy misconception.
People that use MS IPs aren't all employees. You're most likely getting the same trolls you get using IPs from AOL, Google, Comcast, etc. However, that doesn't mean someone working on MSIE8 didn't hate your site.
The way you should address issues in a browser is to always reduce the problem to minimum example code which eliminates people critiquing pages. It's just better form all around and it shows how simple the problem is without exposing the site as a whole.
That's exactly why we have rules the way we do on WebmasterWorld for HTML and CSS, welcome to the reason why.