Can't believe I hadn't thought of posting this before, but I just got reminded of the "vector" hacks that are out there, namely several Atari 2600 ones. Vector Joust doesn't look that great (in my opinion), but Star Trek Vector is definitely cooler! Can't forget the vector hack of Asteroids DC+, of course, and I think Vector SI was imaginative with Space Invaders not only going vector, but having the graphics being black, white, green and orange like on the original.
I also kind of like the landscape on Defender Vector (even though it's a little blocky), but redoing the Stargate sequel of SI Vector Wars...well, that's different! But how come no one's done a vector Gravitar or Battlezone though? And I'd say the same needs to be done with 7800 Asteroids.
And is it just me, or is Donkey Kong Vector just a wee bit creepy?