Lots of vertically oriented arcade games have appeared, including the Raiden Fighters series that ran on the same hardware as Viper Phase 1 yet still saw a compilation release on the Xbox 360.
Nope, there's no need to when we're talking about Gorf for the Atari Jaguar and perhaps nothing else that has been recreated in essentially 100% form by a homebrewer. And I didn't limit it to post 2000 systems, either.
Not sure why you guys are taking an interesting topic and nitpicking it to pieces, but have at it since I've had my fill.