Just as in dictionary, Should new and old always be antonyms

Chennai is a place known for its culture and people here are very proud of its rich culture and tend to continue a lot of traditional practises beating the change in times and pace of modernisation.
Last Thursday, the CM of Tamil Nadu laid the foundation stone of a new assembly building at Chennai. The design for the same is by a German firm, GMP. The entire complex will have two sections- assembly and secretariat. The new secretariat, a towering 20 –storeyed structure, will house government departments and will be one of Chennai’s tallest buildings.
All the newspapers in the city echoed the words on the ministers, calling it an iconic monument and the new symbol of democracy. A budget of over 200 crores has been allotted for the same.
Hats to these foreign designers, (though they are making rapid strides in all upcoming real estates all over the country) who tried to combine both modern and traditional elements. Mr. Hubert Neinhoff, CEO architect-partner, GMP, said that they had to redesign their model on the CMs suggestion and incorporated elements from the structural architecture of the “Five Rathas” at Mamallapuram. A spacious “Citizens’ Forum” has been designed based on the courtyard of traditional Tamil home. The assembly hall will have glass dome. “Sunlight will seep through and provide a soothing effect The legislators will know the weather of the city sitting inside the hall”. (Though I really didn’t quite understand the advantage of this, cause neither does Chennai weather change much all through the year, and even if it changes a little with time, I wonder that the people sitting inside could do about it, apart from getting an umbrella ready before that actually walk out of the building or applying an extra coating of sun screen).
Without taking any credit from the architects, the design on paper looked good and even I am eager to see a new landmark in Chennai by 2010 (“expected” completion time).
But then the thing that struck me the most was the fact that this structure is coming at the cost of death of a colonial-era monument. Admiralty House, one of Chennai’s heritage monuments is being dismantled to make a way for these futuristic buildings. The only thing common between the one structures is that, earlier this monument was famous for it blend of south Indian architectural features and now the modern structure will also implement some native designs.
This leads to number of questions in my mind. Should a new, always replace an old? Do you think that an existing monument should be dismantled out for the new structure? Is it not possible for a place to retain its historic beauty and still progress with its future plans? Cant places promote modernism, and even restore is history and heritage?