It isn't the perfect system. India has long acknowledged that 100% security can never be achieved (alas something that the US TSA has yet to realize), but risk must still be minimized within acceptable limits.

So while a resourceful terrorist looking to detonate a bomb on board can still carry 40 different electronic gadgets aboard(although that in itself might be a red flag for further scrutiny), the system at least makes him have to take them out and reassemble them on board.

Personally, I'd rather be asked to put my loose batteries into my checked luggage than to have to remove my shoes to walk through a metal detector and remove my laptop from its case, but your mileage may vary.