Coming from a traditional art background i will say this., If you want to learn traditional art. Its probably best to learn it the traditional way.
I suppose you can technically use poser or DS as an artificial still life for hand drawing, but I wouldnt recomend it as means of learning for a number of reasons.
1) Unless you have a 3d printer, you would be drawing from a screen or 2d print, which is like drawing from a Book, - which is widely considered bad practice. Ask any art teacher and they will all say the same thing.
Unfortunatly The way your brain translates from 2d to 2d is nothing like the way it translates from 3d to 2d.
While Daz Studio is ‘3D’ in computing terms, its is not 3D in real world terms. To the human eye, its a still just representation of 3d on a FLAT 2d screen.
2) While Its a good representation of 3d and perspective, its by no means a perfect one.
3) Poser Daz characters can and do look rather good - and quite real a face value, but they are still ‘not real’, And compared side by side to real people they look and behave in a very VERY limited way.
4) Posing a Das / Poser character is quite easy, but posing them well (or naturally) really is not, I suppose you could buy pose presets, but even then….
5) The biggest problem of them all - LIGHTING! arrgggghhhh!! :D and this is really a big deal.
3d lighting is hard to master and even when you do, it doesnt behave the way lighting does in the real world, the biggest problem is simply that the 3d universe cannot easily replicate our solar system!
There is no way to tell a 3d program to recreate some global illumination that accurately represents a 1400000 km wide ball of burning hydrogen sitting at about 150 million Km from your scene :D (and lord know i wish there was )
So you have to have to coble together many multiple lights to try and fake it! You can be a master of 3d lighting fakery, but its still not the same as the real thing.
Learning art is pretty much (in most cases) learning how to take something from the ‘real’ world around you and put in to some kind of visual interpretation of your own.
Daz Studio is one such interpretation, hand drawing is another, both are valid in that sense.
But If you are making an interpretation of an interpretation, you are well… effectively cheating yourself out of an important (even critical) part of the learning process.
My advice, get yourself signed up to a life drawing class instead if you can.