"We always knew we were the best associate but we showed how far we were ahead of the rest," Porterfield told BBC Radio 5 live.
"We have made big strides. We thought the ICC were backing us up, we were ticking all their boxes with the things they were asking us to do.
"They have turned around on us and it feels like they were leading us on."
Although Ireland missed out on a quarter-final spot after finishing sixth in Group B, their victories over England and the Netherlands, along with an admirable performance in a five-wicket defeat by eventual champions India, ensured the men in green left a profound impression after their departure from the subcontinent.
However, their performances were not enough to convince the ICC of an automatic place at the 2015 competition in Australia and New Zealand, much to the anger of Cricket Ireland chief executive Warren Deutrom.
"We're outraged by this decision, we're not taking it lying down," he said.
"It's a betrayal of sporting principles and it flies in the face of all the evidence we saw at the World Cup, which was that an associate nation could compete with the best teams in the world.
"It's baffling but am I surprised? Not really, because clearly there are instances where protection of existing privileges is considered more important than any other principle - including those of sport, fairness and equality.
"In the last four years we have been ranked above one of the teams that now has automatic qualification for the World Cup, Zimbabwe, and there isn't a single point you can take from that that is remotely justifiable."
The ICC also announced that the new one-day international league due to run between April 2011 and April 2014 will incorporate relegation and promotion from 2019.
The event is to run separately to the Cricket World Cup to add more meaning to 50-over matches outside the tournament.
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