Totally agree with unzipped.

Above all else: no more Vicki clones. Really, if you're just going to release a figure that's virtually identical to Vicki, don't bother; we already have Vicki. Hint: when getting reference for creating a new figure, use photographs of real people instead of just looking at V3 and trying to "improve" on her.

Is another figure warranted?
Depends on what it offers. Compatability (or not) with other figures?
If Wardrobe Wizard makes it so... It is not other figures that it needs compatability with, but other figure's clothing.

User licence?
Skip making it for Daz then. Make it compatable to the extend that it works through Wardrobe Wizard, or even put out a 'base doll' for it for use in Tailor:
http://www.daz3d.com/support/tutorial/tutorial.php?id=46

Morph injection --- like/dislike?
A near must.

Age? Young teen, early twenties, mid thirties, older?
Default to mid twenties. Morphable to up or down. Most important is reasonable height - make her default at 5'4" or so and not the 50' woman Daz likes... ;)

Realistic or cartoon?
Real, to include anatomical accuracy. The funky morphs and textures used for Daz figures just make every Daz female nude look funny, even from angles where it is 'not the focus' (even in 'R' or 'PG-13' artistic poses, Daz nudes look funky from being female-eunichs in their geometry).

Ease of use.
I've never had this problem. So I'm not seeing the concern.

The most important factor for me though is that the base figure be free and the cost be made in the add ons. Otherwise I don't see it as very viable. Figures like Miki are too far in the other extreme.