I'm not entirely surprised about the lack of backwards compatibility, but it is disappointing.
And get ready for the bigger problem that will certainly result from this. Since you can't transfer XBLA content to the Xbox One, this means that when (not if, when) Microsoft stops supporting the Xbox 360, which will likely include network support, there will be no way to recover your DLC if your system dies, crashes, RRODs, etc. Even if you buy a replacement second hand console, you're basically screwed.
The same will likely apply to PS3 DLC on PS4.
I'm hoping when this comes to pass, more people will wake up to what an issue this really is going to be going forward and push back, but I'm not counting on it.
And now with Xbox One, as per the article I posted a page back (and I've since seen others confirming the same), you have to install all of the games on the hard drive. And if the disc is used in another system on a different account, you have to pay a separate fee. While the fee sucks, that's not my concern.... what this means is that one day when that system is no longer supported, if the system dies, you lose access to EVERYTHING! Potentially thousands of dollars (depending on how many games you "buy") down the toilet all in one shot.
No thanks. We'll see how things pan out with PS4, though the rumors surrounding it haven't been great either.
I'm not liking the way the future of gaming is looking.