Stadium director Peter McKenna told the crowded room that "times move on".
Eamon O'Brien, chairman of the Croke Park Streets Committee, said "there was uproar when he said it".
Patrick Gates, a member of the residents' association, said people were "irate and angry" but measured in their response to the promoters and the GAA.
Nine major events are to take place in Croke Park this year, and tickets to the five Garth Brooks (inset) concerts were sold subject to licence. Promoters have 10 weeks to apply for a licence before the first scheduled gig, and the residents will then have five weeks to protest.
Mr O'Brien said that in 30 years Croke Park had only been refused one application by Dublin City Council.
Representatives for Croke Park pointed out the economic benefits of the concerts to residents, saying 68,000 people have bought tickets from as far away as Afghanistan, and two jumbo jets full of tourists will arrive in Dublin.
The concerts will bring an estimated €100m in revenue to the economy.