To be boring and factually relevant...
NIQ players at Ulster - 6. Leinster - 7, and one was signed as a short term replacement to cover another long term NIQ injury. Munster - 6. Connacht - 8, 3 of them props brought in to cover injury
NIQ players at Aironi - 8. NIQ players at Treviso - 9 (assuming wiki is correct)
So actually, no the Irish provinces don't have more imports.
Also, this season, the following have all been first choice starts for an Irish province when fit - Court, Healy, Best, Varley, Cronin, Buckley, Ross, Cullen, DOC, Ferris, Muldoon, SOB, Wallace, Heaslip, Leamy, Reddan/Boss, Sexton, ROG, Fitzgerald, Trimble, D'Arcy, Wallace, BOD, Earls, Murphy, Kearney, Duffy
second choice behind another Irishman (and a lot of these boys have seen a lot of action because the first choice has been injured) - MOD/Ryan, Toner, Boss/Reddan, Stringer, Hayes
Second choice behind a foreigner - ... well, Horan might have played if he was fit.
So, all in all, Irish teams have less imports than Italian teams and their first choice players are almost all that.
p.s. New Zealand > South Africa. Not a fair comparision.