I believe in being prepared before traveling. Before we went on our cruise last summer, I ordered 300 Euros from the bank so that I wouldn't have to worry right away when we arrived in Europe. We knew going into our cruise that our last excursion would require payment in cash in Euros (about 500 euros). Based on the advice I read, I figured that we would just stop at ATMS while in ports to get the euros we would need.
Though we didn't get currency at the airport (our flight was delayed and our ride was waiting), we started looking for ATMs a few days into our 14 day cruise. Most of the ATMs were out of order, out of money (we had this experience in several countries), or in sketchy areas. So we ended up visiting the ATM in the casino and then taking it down to guest services. It was a TERRIBLE exchange rate. I wished I had just gotten more money from the bank ahead of time to avoid the stress of the whole situation.
Each person has the their own situation and personality. My type A personality likes to be prepared!