Let me also add here, the news is reporting that mobile carriers are going to offer a service to people with these phones to install a new IMEI number on their phone. No details were given (on what i saw) about how this would be done or who is offering this but they mentioned it would cost Rs 200 (~$5), so i don't see this as being a huge deal. Also it was only a couple of months ago that a ban was placed on all pre-paid mobile SIMs in the state of Kashmir since these were being used by many cross-border terrorists, the ban being imposed after repeated requests by the government to the carriers to strengthen the identification process (mentioned by Rexdude above). The carriers could have solved both these problems themselves without the centre having to step in but they did not because it would have cost them customers.
We contend with laws every day that may limit our freedom of choice in small ways but make our society a safer place to live. Frankly i don't care that i can no longer buy a cheap Chinese knock-off phone when nokia sells handsets as cheap as Rs 1200 ($30). There's larger issues to worry about for all of us