I think you can think and still try to do something for your country. The quote isn't about blind loyalty, really.
The fuller quote from JFK (inaugaral speech) is actually:
Ask not what your country can do for you, ask what you can do for your country.
My takeaway from the quote is that it is an imploration for people to think beyond themselves and dedicate their lives to a greater good. The concept is loosely linked to the article I posted here:
http://www.clubsnap.com/forums/kopitiam/1223181-pursuit-happiness.html
I've said this many times and I'll say it again. If you really feel that Singapore is your home, and that you have some vested interest in it - do something today. It need not be big. It can be small. Think that the government isn't doing enough to reach to the less well-off? Make the effort, walk the talk, start an effort to help. Change doesn't always come about through some overnight revolution oft imagined that is the result of watching too many dramatic movies (e.g. Les Miserables). It can, and in many cases, starts small, through individual or small group efforts, before it grows and grows positively into something more beautiful and substantial.
Echoing the multitudes of criticism doesn't do much. Arguing on the Internet serves no one except perhaps yourself. You can do that to blow off steam, to express a POV. But do more. Otherwise it's just a load of hot air achieving nothing but a sense of having done something and effectively deceiving one's self.
Happy New Year to you, btw.