Saan_dai,

I didn't have to go for interview. It is very less likely that you will be
called for an interview unless there is any complication in your application or
the adjundicating officer suspects you of potential fraud in you application.
Beside that, you may also be called for interview if your application is
randomly selected for interview for Quality Control (QC) purpose. Unless you
have done anything wrong, there is nothing to worry about even if you are called
for interview. They will just try to verify your information that is included in
your application.

And yes they want to make sure that you don't look like a terrorist (just
kidding).