It might not so much be that is appeals, just that it doesn't make them feel as silly as it would some over here. I get called a code ninja but only as a joke as I tend to wear black[1] coloured everything at work[2].
In my experience with Indian companies and people of Indian heritage over here, titles seem more important to them generally than to other people I've interacted with. Perhaps due to differences in exposure to certain cultural references "ninja" sounds to them like an exotic title rather than, as it sounds to may of us, a silly one. Having said that, I know people who would appreciate "ninja" in their job title so this is subjective at a more local level too.
[1] Yep, I know there is no evidence a ninja ever wore black, in fact their outfits may have been very colourful: the black stereotype we have comes from how stealth actions were portrayed in stage plays.
[2] I'd prefer a Cash reference but you can't really chose your own nick-names, maybe nipping to Rino and shooting a man would help...
Of course it might not appeal to programmers in India any more than it does to you - it could just be that is appeals to PHBs in India!
