People who detest the GST hike are people who live in relative luxury, who spend WAAAAYYYY too much above their salaries, and who are unnecessarily in credit card debt.
So instead of blaming themselves for overspending, they criticise the G for increasing the GST. They failed to understand that GST are relatively invisible in our day-to-day living as most of the taxes are included in the price tags from the things we buy. They failed to come to terms with the fact that the more you spend, the more GST you pay. And they failed to recognise that anyone who is frugal, they may be only paying 4-5% effective GST, if not less, after taking into account the GST vouchers.
What they are saying is, "I want to live in high SES but I don't want to live with high-SES level taxes". That seems illogical to me, because true high SES, true high-spenders, they don't care about GST. They buy what they want because they can afford it.