I would guess WDW see potential for more revenue at Epcot with Frozen than without it. What were the numbers at Epcot with the M&G compared to before and after it? I would guess they like the numbers they had during the M&G. More tickets, more park hoppers, more people eating in WS since they are there already etc....makes business sense IMO.
As I posted earlier WS is a huge retailtainment area IMO, has been for year. They do indeed want guest to shop and eat more while there, Frozen should accomplish that. But lets not forget we can all buy a cheap plastic pair of viking horns in Norway tonight or a number of other cheap gifts, it's hardly an area set up to discourage us from spending money now. This is just a move to get a more popular item in the area, the number one animated movie of all time no less. I am not buying horns or a Olaf doll myself, but I will stuff my face there