You do not need a night diving certification but taught by the right instructor the course can be a lot of fun and can ease the transition.
That's the way I saw it. While it probably wasn't necessary, I do think it helped to have someone who knew what they were doing there.
The four main differences I found with night diving were:
- disorientation: once I thought I'd completely lost control of my bouyancy and was flying to the surface, in reality I'd floated up a couple of feet: it's tough when you lose sight of the bottom (I was also diving in 5-10 foot vis that night). Your depth gauge becomes even more critical in night diving.
- spookiness: this sounds kind of weird, but things seem to jump out at you and you're not sure exactly what various things are. It's a bit easier to run into things and overall you just have less of an idea what's going on (this would be helped if I had a better light, eventually I want to get one of those nice $500 canister lights).
- having that light in your hand: it's amazing how much more difficult it is to make simple gear adjustments, navigate, etc. when you need to keep control of your light. The first navigation I did at night I was just bouncing off the bottom.
- limited vis: easier to lose others, etc. (this is probably more of an issue in warm waters, vis in Seattle sucks anytime).
Overall it's probably not particularly unsafe to do night dives without training (at least in shallow water), but I do think it helps ease the transition as you said.
And you and I don't know each other, proving my point!
Well two people in this thread have it, so you must just not know the right people