1. A terrorist taking detailed pictures can be spotted more easily. In fact, most Indian government sites (even the international airports in India, in fact) prohibit photography. Same for remote planes etc. IIRC, radio controlled planes required some kind of permit when I was growing up in India. Maybe this has changed now.
2. There is already genuine fucking security in india. More so than you could imagine sitting here in the States. IMHO, the Indian police are some of the smartest when it comes to non-cyber/computer crime. Computer crime is a whole different story :-)

The issue is really that of resources. You don't want to keep a standing army of the top-notch commandos just because the terrorists can analyze the vulnerabilities using the satellite imagery.
As it is, some parts of New Delhi look like a war zone, and I'd hate to see army posts at each intersection asking me where I was going just because they are probable security vulnerabilities. Pretty much the same way I hate it when someone looks at my email logs or the pattern of shell commands or prevents me from accessing certain commands on the system because they may be vulnerabilities.
I can't believe I'm saying this, but under certain (very) limited circumstances it's also about enabling civil liberties (freedom of movement and not being watched all the time) by hiding certain soft-spots that I wouldn't see walking on the street.