People to the parks.

They were originally planned for 3-5 day cruises but we're a hit almost immediately.

They actually had too much demand based on what they could offer. So they kept trying to raise prices to slow it down. However the popularity just kept growing. To make it worse the cruises actually had an opposite result where people were cruising 5 days and then going to the parks 2-3 days.

During this same time park attendance was growing at an alarming rate as well. They decided adding more cruise experiences may keep people from the parks.

Hence came the 7 day + cruises. Customers get the experience of the Disney parks and never set foot in a park.

They also do serve alcohol. They don't offer an all you can drink option but you can buy beer and mixed drinks. I also don't think you get crazy party Mom and Dad but I've heard plenty of stories from Disney folks of craziness on the ships.