Because people sometimes tend to equate "fundamental" with "absolute", and assume that the right cannot be taken away from them under any circumstances. That is not correct.
> You didn't mention what type of restrictions can be put
What is a "reasonable restriction" has not been defined unequivocally - it is subject to interpretation of the courts.
An example is Article 21 of the constitution: No person shall be deprived of his life or personal liberty except according to procedure established by law
So a person's right to life or personal liberty can be restricted according to procedure established by law. That is why you find people in prison. Their fundamental right to liberty is restricted by a procedure established by law. Similarly, the fundamental right to privacy can be restricted by a procedure established by law.
"... the State can impose reasonable restrictions in the
interests of the sovereignty and integrity of India, the
security of the State, friendly relations with foreign
States, public order, decency or morality or in relation
to contempt of court, defamation or incitement to an
offence."http://planningcommission.nic.in/reports/genrep/rep_privacy....
Please read what he said, he is not saying that, the thing he quoted is, and that thing I believe is the constitution as it stands now.
Asserting it as a "fundamental right" raises the bar on what restrictions can be put. But reasonable restrictions can still be put.
A separate bench of the SC is now going to test the validity of the Aadhaar Act on the basis of whether the restrictions are reasonable in the light of privacy being a fundamental right.
Edit: The Aadhaar Act is an act that allows for the government to collect biometric and other personal data that can be used to identify an individual for various services (including but not limited to governmental benefits).