I think the biggest problem with DD+ is adoption. Most people tend to believe the codec is only geared for 5.1/7.1 cinema audio. The idea behind the concept is to allow for virtual surround using the integrated technologies present in the stream (and yes that includes Stereo 2.0 Audio). Also, DD+ can be passed through a mobile stero device to an AV receiver for true 5.1 surround even if the mobile device itself cannot support multi-channel playback. This embedded technology is one way in which this surround format has the capability to enrich streaming media well beyond the typical restraints of stereo audio channels. In short, it simply enhances audio to high-fidelity audio without the high bandwidth requirements of some of the lossless formats such as FLAC.
There's a very good reason why we have XDA communites out there rooting their android devices just so to port over the codec from other android devices that come standard with the codec. I'm pretty sure those folks are not going through all that trouble just so to find out that the codec doesn't improve their stereo quality.
The AptX-HD codec does indeed require both the transmitter & receiver to have the codec installed, but that shouldn't be a reason for anyone to shy away. It's just a matter of time before a couple of high-end Bluetooth Headphones start carrying the codec. The update might be a little slower for car audio, but then again that's to be expected. Maybe if we get lucky, we might get the codec on a couple new cars like the Q60 that carries the all the new Bose Performance Series. The whole discussion about Sound Quality is entirely somewhat subjective, I have a buddy who swears behind the Burmester on his Macan, and I presonally don't agree with him. It's not a big deal, it's just a preference. We even have folks out there who would swear behind Viper 4 android, and again that's not for me, the sound doesn't seem natural, and there's a lot of tweaking involved. Before going through all that trouble, why not simply rely on a certifed industry standard for audio that's trusted by many such as DD+?
As for my lovely music collection, it's all an asortment of 128-320 kbps mp3s, and a few FLACs. Like most peple, I stopped carrying CDs a while ago, and it's too late to go back. FLACs are great, but most of us still have to deal with old mp3s hence the need for DD+.