I think we just view Bass and Hansbrough's relative trade value very differently.
Hansbrough has upside because he's only been in the league 2 seasons. Bass has been in it for 6. Years spent in the NBA mean a lot more in terms of development -- as a professional basketball player playing NBA basketball -- than age or years spent in college.
I think you're really wrong, though, about getting a player of Hansbrough's production for less then $3 million. This off-season, for example, the Celtics got Wilcox for $3 million, which I think may have actually been a little bit below his market value. Wilcox is not nearly as valuable a player as Hansbrough. Glen Davis is getting paid $7 million a year, and he's not as good as Hansbrough. Bass has similar value right now, with less upside, and he's probably going to get a 3-4 year deal at $7.5-8 million a year this off-season.
What skills do you anticipate Hansbrough developing? He's a known quantity. He's been playing the same way for years.
Wilcox, McBob, Reggie Evans, Kurt Thomas, Brandan Wright, Kenyon Martin, Lou Amundson, Mo Speights, Dante Cunningham, Nazr Mohammed, Aaron Gray: all were signed/acquired for around what Tyler makes. A decent roleplaying big man does not have to be expensive.
There's a reason why contracts like Baby's and Gooden's are viewed with such disdain.
None of the players you mentioned are as good as Hansbrough or Bass.
There's a lot of hate about Gooden's contract, but I think he's shown this season filling in for Bogut that he's a very talented player.
Hansbrough has shown flashes of an ability score in high volumes (had stretches last year where he was scoring 20-25 pts a game), and I think it's reasonable to expect that his jumper could gradually become more and more consistent. Players like Ty add 3 point range frequently, even later in their careers.
I don't think Ty is ever going to be a star, but considering he's averaged 17.2 pts and 8.6 reb per 36 minutes over the course of his 2 and a half season career, expecting that he could one day be a scoring PF along the lines of Carl Landry doesn't seem unreasonable.
He just needs to improve his shooting percentages -- which, like Bass, might happen if he simply gets to play with a point guard who can actually pass.