In the '80's the NDP had banners at all the rallies not so much anymore.My guess would be that many of the fiery idealists from that era have since retired or died off, and what we're left to contend with is the cold pragmatism of collaboration. The earlier passion of the NDP's activism in support of the debate surrounding real questions and solutions has been replaced by a passion for seeing debate and activism shut down as soon as possible.
Which is why you don't need idealists. What you need are people with a solid hard headed analysis. Having someone in parliament who could accuse the Prime Minister of being a "fuzzy headed idealist" for believing you can successfully "build schools in a war zone" would wound the Tory ego far more than accusing them of deceit. Deceit because they know better than everyone else is in their playbook as a virtue.
Making Harper appear soft and naive would hurt Harper's ego and would bare more fruit than having Layton an co. feed Harper the rhetoric of "humanitarian intervention" as a casus beli for nine years.
People will vote for hard headed pragmatist over nice guys, any day of the week.