Being blunt - I agree with SEOPub on this... but I do have some concerns re: anchor profile which I will come to in a bit... As mentioned NOFOLLOW links do not pass link juice period...
In fact if you just focus on DOFOLLOW links its inevitable that you will pick up nofollow links whether its from forum, social media, video marketing or other sites etc... Its just a matter of time... Regarding link profile your anchor text diversity is important due to penguin, so I would focus on that in addition to seeking high quality backlinks from sites which G considers authoritative... However that's specific to ranking on the SERPs...
I also feel its real important to diversify your traffic sources so that you do not rely soley on G... Adopting that approach you'll find that you will for sure pickup NOFOLLOW links... For me as long as that carries traffic then I'm real happy i.e. youtube videos, ads, social platforms, web 2.0, blah, blah... etc...
Aiming to get Nofollow links for the sake of nofollow is silly.... Aiming to get links which carries traffic regardless of nofollow, dofollow is a good thing, but one should be aware of the difference when examining ranking positions on the SERPs...
The one question I do have is whether NOFOLLOW anchor text contributes to a backlinking profile which G's penguin algo picks up... I'm not sure but suspect it may... Hence its relevancy to backlinking profile and with it either it contributing to it looking natural or raising a red flag.... For example lets say you have too many commercial anchors which contributes to an algo penalty... One example is whether nofollow links with varied anchor text can dilute that and thus helping you to keep away from penguin? Curious to hear of opinions on that one....
So I suspect there is much more to consider wrt backlinking profile and with taking steps to ensure that it keeps under G's radar, especially when you consider anchor text density ..... I also suspect nofollow may also play a part of G's algo with spam detection.... I dont see why not given its really easy to include nofollow anchor text as part of the algo....