I find it very strange that they decided to moved it since the Dhoby Ghaut area is pretty dead.
If they had kept it there, there'd be one more tourist attraction other than the Istana
I think you are confusing the tank road temple with the one in Chinatown that's called Sri Mariappan temple (which is also there today). The one in Tank road has always been there. It was renovated more than 20 years ago but it has never changed location as far as I know. That temple is the end point for the Thaipusam festival that devotees undertake.