I don't reckon Namco would be ashamed of Soul Blade. For a game initially released in 1996 it was quite impressive and Namco should be proud of it. I guess the leap in quality between Soul Blade and Soul Calibur means Namco distinguishes the two as seperate franchises.

I haven't played Soul Blade in a looooong time (probably as far back as the late nighties) so I can't say whether Namco has even acknowledged the games existence in the Soul Calibur series. All I know is that without Soul Blade we wouldn't have Soul Calibur so whether Namco is ashamed of the game or not, its a pretty significant game in their portfolio.