I was wondering whether we really need to use 'past perfect' in the following sentence -

I completed my studies before I moved to NYC.

- doesn't 'before' tell us which action happened earlier ? I think, it does; and therefore, we needn't use past perfect.

I had completed my studies before I moved to NYC.

- Sounds ok, however, 'before' and 'had', both of these play the same role of telling us more about the event that happened earlier in time.

Is using 'had' all about emphasizing the time span between the two events ?
The past perfect is unnecessary with 'before'. If used, it does not emphasize the span, but the completion of the earlier event before the advent of the 2nd event.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Did you mean 'before' ? 'for', to me, indicates a time span.

I wanted to know more about the examples that I mentioned.
Yes, sorry. Typing error (which I have now fixed).