I was about to express surprise to learn that Maya, 3ds, etc could use daz content natively, since that's rather a large component of what I mentioned went into that little test sample, but then reading to the end of your paragraph and sounds like I'm not wrong about that and they cannot use Poser/daz content natively (please correct me if I'm wrong).  I realize you personally don't care about poser/daz integration and that's cool beans.   Whatever works for your particular pipeline and is the best for you personally, it's all good.  :)

But at the same time, for a general discussion of what's going to be useful to the market at large, having a huge premade library of high quality and ready-made content ready to go and work natively in your preferred application is (without question) a tremendous benefit.  There may be certain situations where it makes logical sense to build every model in the scene from scratch, but for most of us that's a huge and unnecessary task that will kill a lot of project time that could be better spent getting to the final render and composition.  For myself I don't have the skills in modeling, or the patience and love of modeling  to do that, and would consider it an insurmountable obstacle/time killer if I were forced into that position in using an app that can't make use of the huge existing library of poser/daz content that is already ready to go.  Carrara can do this, and the list of other apps that can dot this is pretty small, and this gives great value to what Carrara can do (to the objective market in general, not you specifically).  I wouldn't own and use Carrara if it couldn't use the daz/poser content natively, for example.

 Also I would point out that by bringing Maya and 3DS into the discussion you're now comparing a $65 application (Carrara) with apps that cost thousands of dollars.  The fact that Carrara can stand up to the comparison at all with such more highly priced software is astounding.  Carrara is certainly not aimed at the same market segment as those who have gigantic blockbuster budgets and need a full production studio with software to match. 

 Blender is definitely better at some things than Carrara, but fortunately it's free, so anyone can integrate into it into their toolkit.  I would say it's decidedly better at fluid simulation, for one example.  Blender hair is pretty good for stills, but I haven't seen anyone using it for animations where it looked realistic in the way it draped and behaved on a human.  That may simply be user error, or that no one has yet 'broken the code', so not a value judgment on Blender's hair system itself, but Carrara hair sim is nearly realtime, incredibly fast, and realism-wise is on par with programs that cost thousands of dollars.  I think you mentioned before you yourself are not into animation but stills, so fair enough you probably can get just as realistic looking hair from Blender, but objectively speaking for the broader audience, if Carrara can do more realistic hair sims more quickly than Blender and give realistic animations quickly, then even if it's a 'dead heat' to how realistic the hair looks in still renders I think anyone would agree that's an edge to Carrara. 

 At some point someone somewhere will probably add to Blender the  ability to use the daz/poser content natively.  If this happens, it will undoubtedly change the game and the current landscape, and may mean that Blender will eventually become the the more popular all-in-one solution that it certainly can be.  But at present, I'm not aware of any other program that can do the whole of what I did in that simple test animation, quickly and efficiently.