Actually the first 3 images were found doing a search for "Wormhole" via Google images.
The second image is actually the Bajoran Wormhole from Star Trek: Deep Space Nine
Considering the gravitational forces we deal with in game when in a "Wormhole System", these "Wormholes" seem to be a mix of both Wormhole and Black Hole characteristics. Therefore, I see no problem in mixing the visual style of both either.
Ok, yes, so would I. But I'm only talking about what we have now. I don't know if I'm alone, but, I'm just not a big fan of the rainbow wormhole. And I was hoping a skilled modder or two could give us a different look or so.
I always felt like those blackhole systems should have a lot of risk in going through them to jump from place to place and normal wormholes should turn up randomly between 2 points for up to a few hours at a time and only try to drag you in when within a few sectors.