Well, I guess it's the reason I never became a game designer. That's really strange though, because it seemed like D20 came on like gangbusters, and is still around. Or am I not reading that correctly?
D20 sci-fi games struggled badly.
The only really successful Class/level/skill sci-fi have been T20, the various Palladium games, and the M&M superheroes.
D20 Sci-Fi has generally been meh -
T20 wasn't close enough.
D20 Star Wars wasn't a great Star Wars.
SWSE was prototype 4E D&D. It has its fans... Staunch, but not enough to renew the license...
D20 Fading Suns was a bomb-out.
Dragon Star went no-where, and fast.