I went to Phuket for New Year once and didn't enjoy it that much. It was full of miserable European families.............and don't get me wrong, I'm from Europe too, but there was something weird about them - you'd think they'd be happy that they were away for Christmas but apparently not
Anyway, the whole gala dinner thing is a complete rip-off, the price of staying in a mid-range hotel for the night for some of them and often don't include any alcohol in that vastly inflated price. One family I spoke to refused to pay it and got away with it, so perhaps upon booking you could do the same.......either that or stay in a place that's cheap (they don't usually do gala dinners so you can go and eat somewhere nice instead).
Actually, perhaps that's why the European families looked miserable - they'd just done a currency conversion on their 'Gala' dinner price